Pond Boss Forums Thread Like Summary - Draining (Siphon) Pond

We have a 5 acre pond that we are looking to drop around 2 to 3 feet in order to clean out the head water as it has accumulated silt over many years. The middle of the pond is roughly 15 feet deep. I have placed the head of my pipe roughly 15 feet from the bank into the water and about 3 feet deep. The pipe then runs uphill about 155 feet to a T which is at the peak of the hill and used to pour water in to fill up the pipes. The pipe then runs downhill to the drain end 180 feet where I have it capped off until I have the pipes fill with water and ready to release in order to cause a siphon effect and pull the pond water out.

I am running into an issue on the pond side of the T. The water seems to be draining into the pond under water and not holding in the pipes. As mentioned, the pipe is underwater about 15’ out from the bank and 3’ deep. I would think that the pipes would be full of water up to that point and not capable of being pushed out because of all the water pressure in the pond. Also, I have checked for pipe leaks and there appear to be none.

Can someone please help with any suggestions on why that end of the siphon is not holding water?

Diagram to help future readers: note that water must be added to fill area such that air can escape (not a sealed connection).

Looney tunes? More like hold my beer and watch this

We use what they call backflow preventers, aka checkvalve, on 4" sewer lines coming out of houses to prevent the city sewer from backing up into and flooding your house when there are a lot of houses on the same sewer line that are at a much higher elevation then your house, but they are a little pricey, any kind of valve or cap would work but you must be able to get down under water to open it almost simultaneously with the opening of the valve on the backside of the dam.
JPsdad, in this case, the way I understand it he is using hard pipe, probably pvc, which will be harder to fill and then pull over the hill, especially 335" of 4 inch pipe full of water. pvc is what I have always used, with a few bend fittings if necessary, and the pipe can be reused for something else afterwards.

Jscummy,

Sounds like your configuration will work for a siphon. I also like that you are using 4" pipe.

I agree with gehajake that using a check valve on the pond inlet side will make your life easier.

The low pressure type that you need is usually called a "backwater valve". You should be able to find one at a big box hardware store. I see $33 at my local Menards and $58 at my local Home Depot.

However, be advised that the female connections on the backwater valve are made to fit DWV pipe. Are you using PVC schedule 40 for your siphon pipe? If so, note the type of pipe you are using and test a piece of that pipe at the hardware store to make sure it fits your backwater valve. (I have had fittings NOT fit the pipe when trying to mix large diameter SCH 40 and DWV pipe.)

This one says sch 40: https://www.menards.com/main/plumbi...lve/869-s4ppk/p-1444442707301-c-8632.htm

I think the pressure at the check valve will be based on the distance from the top of the tee to the water surface and come from the pipe side, not the pond side. The amount of the draw line that is underwater does not matter. My gut feel is that the 5 PSI max on the flapper check valve should be fine. I would be more worried that the siphon might not pull open the flapper, but I am guessing it will work fine too.

RAH, I think the flapper will be fine, its a pvc flapper and will all but float open and let gravity water thru, in his case he will have considerably more pull actually enough to pull the water up an 8' elevation by dropping more then that down the other side,
Like Esshup said, the vortex it creates could be a problem, I think if he is far enough underwater it should be fine, there is not a lot of velocity, just a steady flow, even then, it will take a little while to lower that size body of water several ft.

Buying an ATV or side-by-side to prime a siphon sounds pretty fancy to me:)

I am pretty sure you have several deer on your property that could tote that rope.

Unfortunately, it would probably take several Pond Boss threads to come up with a reliable way of harnessing your big bucks!

The more obvious answer to this scenario would be a to use a muskrat, a big one should just about fill up a 4" pipe, that would work for the pig and everything, might tie a rope around his neck so that you can give him a little assistance around the elbows and everything. if he didnt fit tight enough in the pipe to drag water you might let him lay in the sun for a couple hrs, he will tighten up good.

Love the muskrat idea.. If you get a live one motivated enough he may do the work for you..

Yes sir…. But physics is physics..