Pond Boss Forums POND CONSTRUCTION Building a dam Steel Siphon System?

Has anyone here installed a siphon system made from steel pipe? One of the contractors I have talked to is concerned about PVC holding up to the vibration. NRCS wants a 24" pipe if conventional overflow system is used on the pond I am planning. I'm thinking a 14" siphon would discharge the same volume of water and the pipe would cost a lot, lot less. Welding the pipe is not a problem, but I'm unsure about the details of valves and vents when working with steel pipe. If you have a siphon system made of steel pipe instead of PVC I would love to see some pictures.

Lynyrd, You can install the pipe so that it is buried going up the face and down the backside and vibration is not an issue. Easier to mow grass that way, too. Except where the horizontal section goes through the top of the dam, I think my pipe runs about 2 feet below the surface.

Vamaz, how much fall do you have from pool level to bottom of outflow pipe? And what sized pipe?

I used 12" Sch 40 and IIRC I have 5' of fall from inlet to the bottom of the 45 degree elbow on the outlet.

I'm curious how you've determined that a 14" siphon will move as much water as a 24" conventional pipe (drop=inlet, I assume)? The reason I ask is when planning my pond I was never able to find a calculator tool on the internet for estimating flow rates through a siphon, just tools that would base the rate on diameter of pipe, type of pipe, and fall.

I ended up buying the largest diameter pipe I could reasonably afford and then used the USDA handbook, "Ponds = Planning, Design, and Construction", to size the emergency spillway.

I got this formula for a conventional overflow pipe from the NRCS.

Water Flow Formula : Q=6.17(diameter to the 1.25 power)(height to the 1.35 power)

And this link will show you water flow through a siphon.

http://extension.missouri.edu/publications/DisplayPrinterFriendlyPub.aspx?P=G1531

After studying the numbers longer, I'm pretty sure that a 12" siphon will release more water than a 24" overflow. The water height coming over the edge of the overflow is the main problem with overflow pipes, and very hard to predict or measure.

I've been looking at this for over a year, and I'm still not sure what to do.