Pond Boss Forums POND CONSTRUCTION Building a dam Siphon specifics

OK... Now that the water is cold enough to be really enjoyable when we fall in, I've finally gotten almost everything I need to start the siphons.

Details:

Dam is around 212 feet thick (or maybe a bit more) at bottom tapering at approximately a 4:1 slope (on both sides) to the top where it is somewhere around 12 feet wide (or a bit more).

There is currently 5 to 8 feet of freeboard between dam top and water level (not quite full and spillway is 5 feet below top of dam).

I'd like to pull about 15 feet of water out of the pond.

I have 600 feet of 8" diameter pipe (30 twenty foot joints).

I have pipe soap.

I have four 22.5 degree elbows.

I currently have one pipe saddle (allows one to cut 2" diameter hole in pipe and add that size pipe going upward).

I have 2" ball valve and other 2” pipe to connect to 2" water pump a friend has.

I have some inflatable balls and such that I'm hoping will plug / seal the ends well enough (with reinforcements from vice grips / wire / whatever else if necessary) to keep water in as needed to start siphon.

Questions:

It seems I read on here that a siphon won't pull more than 20 feet vertically. Is that correct?

What is the best use of the pipe? I.e. Do I have enough 8” pipe to do two siphons? If so, how much pipe on pond side and dam side?

Is it likely the pipes will stay together based upon friction or do I need to screw the pipes together with stainless self tapping screws or something (I can email pipe pics if that helps)?

Will those inflatable (dodgeball type) balls work to hold back water with something across them (rope with vice grips or something). I don't really have a lot of confidence in that, but 8" check and ball valves seem pretty expensive for very infrequent use like this. Do you have other suggestions?

Should I should use floats / weights on pipes in water to suspend them below the surface, but off the bottom?

What should I watch for as the stage where hypothermia becomes severe?

Also, any idea of, at what point, ice might pose a risk of cracking the pipe? It should be close enough to bank so that I can chop around it and water flowing through wouldn’t form ice, but just wondering in case siphon not working for either 8” or 14”…

Speaking of the 14”, I still haven’t gotten all / enough of the 14” pipe I ordered long ago; but am pretty confident in how to make it work (except for whether I need to use screws to hold together and floats/weights).

Thanks!

Jeff

Jeff,
Not certain about the 20' of vertical but sounds right.
I'd suggest getting 1 siphon going, then seeing.
The further you run down the back side the faster it will pull out the water.
The front side needs to extend down to the depth + 4' extra or so. If it whirlpools and sucks air around that suction end it will break the siphon.
Would add 1 or 2 screws to the pipe joints of the pipes in front. Keep them together if you want to pull them back out. Insures the weight of the water won't pull the joints apart, with the pipe laying on slime it would slide easy.
The balls should work. If not 8" inflatable pipe plugs are available for testing pipe, or could glue a cap on downstream end and saw it off after priming pipe, but that getting wet- hypothermia thing comes to mind. 8" ball valve would work on front right below water level.
If you can get the pipe ran into the pond without plugging the end up I would think it would lay on the bottom and siphon without any problem of plugging up.
Pipe is pretty tough, should withstand freezing unless severe.
Hypothermia is one thing to watch for, 2 other things in regards to safety: If your dressed heavy with heavy boots and the front of the dam is slick, sliding into the pond could take you under for the count. Also after getting siphon going do not get close to suction end. If it grabs you you may not get loose, especially if your in deep slime.

Thanks zhkent!

Just an update: Yesterday at 2:40 p.m., we started the siphon on the first try. We had the basketball in the downhill side and the dodgeball in the pond side both pop out while filling with water. We had to put straps over the ends to hold them in. I bought a bunch of stainless screws to hold the pipe together, but we wound up driving several steel posts alongside the pipe and strapping the pipe to them so they wouldn't go downhill instead. I'm glad we did that as it worked fine and I don't have screw holes in the pipes. I bought a 30 x 60 tarp to go under exit and help minimize erosion. That was a good idea. Water is shooting out of there like crazy. I was seriously impressed that it elevated water levels and created current in the creek 1/2 mile downstream like it did. This morning, at around 7:40 a.m., the water levels in the pond had dropped about 6". It has quite a ways to go; but we're going to have add more joints to the pond side to get it really down there. I'm already dreading that. The water was cold with just my arms in it (off pontoon boat)! I can provide more specifics and some pictures if anyone is interested.

I am interested in seeing the pictures, Ranger.

Me too.

As Kent said -- keep away from the suction end of the pipe. When you go to add pipe to that end watch out. You do not want any arms, fingers, cloths or any thing else in the way. It can mangle a hand or kill you if you get them in the suction and the pipe attaches (is sucked on). You can't pull your hand out of the suction of a 8 in. pipe!!! Take 2 lengths of pipe connected put wire or strong rope harness ( so that the harness handle is 3-4 ft. above pipe) about 3 feet back of each end and submerge in water until full at least 30 ft away from suction. Slowly line up new pipe and move toward the suction end holding on to just the harness handle and guide into place until suction is on far end of new pipe # 2. NO CHANCES HERE YOU MAY NOT GET A SECOND ONE.

As the water level goes down the speed that it drops will increase because the basin of the pond is smaller.

It sounds like an emergency "break suction" valve/fitting at the top of the dam, with a live body standing by to use it, would be a VERY good idea while messing with the inlet of an operating pond suction.

I'm not sure why you wouldn't be able to run a siphon over 20' vertically. As long as you could build a pipe to support the two water columns, I don't see why you couldn't run a siphon over the moon and back, as long as the head pressure of the siphon (elevation diff) is enough to overcome the friction losses in the pipe.

I think I may try to put a metal plate of some kind where the water hits the tarp to help disperse the impact (afraid I’ll soon have an extra holy tarp if I don’t). I’ll have to try that method to add pipe to the end if get to it before siphon stops. I used a fillet knife duct taped to a piece of 1” PVC pipe to puncture ball when nephew opened lower end. Nephew wound up having to cut one of the straps to open lower end. When he did, the basketball and water shot out. I couldn’t tell if I had successfully punctured the dodgeball or not at first. It was in the ditch below though before I could make it back to top of dam. We used the 2” pipe saddle and valve to fill up the pipe with water pumps and shut it off when it was full. It could be opened to break suction in emergency.

Here is my first real attempt at posting pictures on here... The pictures are fairly small (shot with Treo phone). Hopefully, there aren't so many it is slow for slow connections.

Tn Hillbilly- The hight of lift will only be limited by the vapor pressure of the water. In other words the point of vacuum where the water starts to boil or vaporize. I am sure this is higher than 20' at normal temperatures.

The upper lift limit for a siphon is the atmospheric pressure expressed in feet of water, approximately 30 feet (as opposed to the 29.5 inches of mercury the barometer on the wall next to me is reading). Temperature does not get into it (except that it's hard to siphon ice).

I believe increasing the height of the drop on the outlet (greatly in excess of the height of the inlet rise) may increase the rate of flow. It will not lift water more than the atmospheric pressure (30 foot) lift limit.

Thanks for posting the pics, Ranger. That's a lot of pipe and a lot of water flowing out.

Pondsforfun,

Good point!

Theo,

One standard atmosphere is about 33.9 ft of water, but why couldn't a siphon pull an even lower pressure than that? A lot of pumps can draw water up much farther than that, which means they can create more than 1 atmosphere negative pressure, without the water boiling. Whether or not the siphon will flow and the flow rate is simply a function of the head pressure right? The pressure (negative) in the pipe doesn't have anything to do with it until as pondsforfun said, the the pressure gets so low that the water at the highest point in the pipe starts changing state to a gas. Maybe I'm missing something here.

Rangersedge,

Too bad you don't gave a generator on the end of that pipe!

Rangers Edge,

I am having to do this same project for one of my customers. I have to plan it out and quote it today.

Any "after-the-fact" knowledge is very helpful!

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The first photo is of the overall pond, 1.21 acres. The problem is the drain pipe is clogged and deteriating. Water is passing by the pipe and most likely erroding around it.

We need to lower the level in anticipation of heavy rain fall so the system does not over flow and use your idea until the customer can locate a firm to correct the problem.

TNHB:

Submersible pumps can be sized to push water much higher than 1 Atmosphere (we'll use your 33.9 feet, since it's more precise than my "about 30 feet") - pressurize the water more and you can push it higher. But above water suction pumps cannot raise water more than 33.9 vertical feet, because they only have one atmosphere of pressure (literally from the actual atmosphere pushing down on the water) to work with. And a siphon follows the same limitation.

I have never heard of water boiling in a siphon or pump.

Theo- You can use a vacuum pump to make water boil at 32 degrees. When you raise water up a vertical column by suction or siphon the higher in the column the more vacuum pressure you exert on the water. When the water reaches its vapor pressure, the point where vacuum and temperature produces vapor, It will boil or vaporize and lose suction. This is true of any liquid except they all have different vapor pressures. The atmospheric pressure and gravity keeps everything from boiling away. Or at least it was that way when I went to school. :p

Theo,

You can buy pumps that lift much higher than 30 ft. I'm talking about the pump on the high end of the pipe, pulling water higher than 30 ft thru the intake line. I don't think the siphon cares what atmospheric pressure is since it is the same at the inlet and outlet. Atmospheric pressure cancels out. It's the difference in the water column heights at either end of the siphon that is providing the working pressure, so if I have a difference of 50 ft between outlet and water level on the uphill side, I should be able to siphon over a 49 ft dam. I've never heard of water boiling in a siphon or pump either, which tells me you can run a siphon over a great height, or pull water up with negative pressure up a great distance without any problems, as long as you can build a pipe to do it.

It is true that you cannot syphon higher than 33 feet based upon what you guys are saying about vapor pressure. See this site:
http://www.exo.net/~pauld/physics/syphon/syphonphysics.htm

bz and Theo,

I stand corrected. My apologies.

Cary: Sorry I didn't have a chance to check this out until now. A nephew called last night about fishing this morning and it worked with my schedule so went fishing until noon and was then busy until a little bit ago. That looks like hilly terrain. If you have enough downhill slope, I think a 4" pipe would probably drain that pond pretty low, pretty quickly and would be a lot cheaper / easier than the bigger pipe. With smaller pipe, you could possibly, affordably use a real check valve on the water side and a ball valve on the dam side to make it a one person job instead of a three person one. With smaller pipe, I'd get a T and small valve for the middle of the dam and use a small gas water pump / hose to fill. That way, a person shouldn't have too much money in the siphon / supplies and one person can easily redo in event it fills back up before contractor fixes the existing. Even with smaller pipe, you'd want to keep it from coming apart so I'd connect the pipes with either self drilling screws or stakes / straps like I did. If I used the screws, I'd probably still put a stake / strap on the bottom end.

Wish I had you guys around to help out about 20 years ago, fyhsics would of been alot more fun.

fish and fhysics.........who would of thunk you'd get that all here