J. White here. Living in Western North Carolina. Bought property with 1/2 acre pond in disrepair. Getting ready to rehab and I am looking for a website that can give me ideas for the overflow design. The existing one needs to be replaced as it is rusted away. I have seen one that comes up out of the water and 90s back down so to siphon the water from below the surface, thus leaving oxygenated water on the surface. Thanks for any advice. J. White
If you google "bottom withdrawal spillway" there is plenty of reading material. This diagram does a good job of explaining how it works:
http://www.georgialandsales.com/pdf/PondSiphonSystem.pdfI chose to go with a standard "surface withdrawal" spillway pipe angled through the dam in my project.
edit - oh and welcome to Pond Boss! plenty of great reading here too!
You might want to check out Agridrain. This is what I put in my pond and it works nicely. It has stop logs that can be added or removed to adjust water level to the desired height. Depending on how much water comes into your pond and how you size the overflow pipe it would be a good idea to design some type of emergency spillway just in case the water ever gets too high.