Installing pond outflow question

[Boondox]

Like most properties in this area, I have a pond. It's about 80 feet in diameter and about 8 feet deep. The berm is packed earth/clay, and the pond was built about 50 years ago so it's very stable.

But the overflow is thru a 12 inch culvert placed so close to the ground's surface that every winter it gets pushed up by the freeze/thaw cycle till it doesn't handle any overflow at all. And with all the snow melting, then the spring rains, that's exactly the time of year I need the thing the most! For a couple of generations now we've solved the problem by using 2" PVC lines to siphon off a couple inches after every rain. I'd like a more permanent solution.

Since a 2" line is adequate, I was thinking 4" heavy walled PVC would be fine. The berm nearest the stream (where the overflow dumps) is 24 feet thick. What I was thinking of using is essentially a 30 foot long section of PVC with the entire length angled downhill and the end sticking up at a 45 degree angle, sort of like a long hockey stick. With all the leaves we have each autumn any strainer would quickly be blocked, but with the pond end angled like that my thought was the water would start flowing the moment the level rose to the lip of the pipe...and if the water rose further it would reach the wider portion of the pipe and more would be able to flow. I hope I described that okay.

But I can't just dig all the way thru the berm in one shot, or the pond will drain out the ditch. Lowering the level isn't an option right now because my infeed was washed out and has to be fixed or I lose a lot of critters. What I was thinking was I'd dig half the trench, install the pond half of the PVC pipe with the end capped, bury it--then dig the other half, join the PVC sections, bury it all, and uncap the end. Would that work?

Is there a better way?

TIA, Pete

 

[VABlue]

There is no easy way to put in drain pipes, other than to hire someone with a hydro drill to go straight through the berm. Think of the way fibre optic cable is buried...

I don't think 2" pipe is big enough to keep up with a heavy rain or ice melt. I'd go with 4" at the minimum just to be safe. And that is just to keep the pond at a certain depth. The 12" overflow culvert needs to stay in place for safety. Heavy rains and snow/ice melt can easily overcome a 4" pipe and the water will then run over the berm and possibly wash it away. If it's too high to be useful, it needs to be replaced. Those berms will wash out too quickly if you don't keep up with it...

 

[Dirthog]

The other reason to use a larger pipe it to help keep the top of the pond cleanas the water starts to flow out the pipe it suck the leaves and debries out it

 

[john_bud]

But the overflow is thru a 12 inch culvert placed so close to the ground's surface that every winter it gets pushed up by the freeze/thaw cycle till it doesn't handle any overflow at all.
TIA, Pete

Why not just fix the current overflow so it works, then top it with enough dirt to move the frost line down to a point where it won't freeze?

jb

 

[Boondox]

Why not just fix the current overflow so it works, then top it with enough dirt to move the frost line down to a point where it won't freeze?

jb

On that side of the pond the water comes to just about 4 inches from the top of the berm. If I move the culvert deeper, I'd lose a lot of pond. And with the precipitous dropoff into the stream there's no way to build the berm high enough to put the culvert below the frost line. I just don't have that much dirt!

 

[MarkV]

Hi Pete, good to hear from you. Hope all is well in the mountains. I’ve been thinking about your plan for a few days and what I come back to is, when you dig that soil to put the pond section of pipe in I would think the ditch would fill with water and saturate your fill. With it saturated I would be concerned it would not compact well enough and be a weak spot in the dam. If it has to be done with out draining the pond at least partially, would it be possible to put three sections in with the last being a short section at the pond? My thought is that if the majority of the pipe were installed, filled and compacted it would work as a dam to hold the water back for the installation of the short section. Possibly even reinforce the end where the short section attaches with bags of concrete.

I’m sure you know there are many ponds without an over flow pipe at all. Is the use of a spill way possible the way yours is configured? Our pond is about 4 acres and uses an over flow pipe as well as a spill way that comes into play when the water flow becomes to much for the over flow pipe.

You may want to ask your question at www.pondboss.com in their discussion forum call “Ask the Boss”. Good people over there and a good number of pond management people participate.

Are you sure you just don’t want to dig with that new excavator?

MarkV

 

[mj1angier]

you can try this: Conventional Pond Piping System
Or http://www.rodneyhunt.com/Anatomy_sluicegate.pdf

More info : http://www.ext.vt.edu/pubs/fisheries/420-011/420-011.pdf
http://www.mdc.mo.gov/documents/fish/pondhb.pdf

 

[Boondox]

Mickey -- Good links, thanks!

Mark -- To tell the truth, I AM having a lot of fun with that excavator! Planted my 1957 Dodge truck up to the fenders in the meadow like it ran into a big boulder then sank in the mud. Built a dam. Cleared the ditches of silt. Harvested several boulders and planted them on the bank of the pond. But I think it's time it get used for a project that's actually needed.

You make a good point about the fill being saturated. I hadn't thought of that.

I wonder if I could use boulders and fill, redi-crete, etc to create a coffer dam where the pipe will enter the pond. Then I can dig and place the pipe properly.

Thanks!

Pete

 

[Egon]

I like that spillway idea. Any chance of pictures?

Oh - and whats new on the " tools " list for this year?

 

[RonMar]

I was going to suggest a siphon similar to that pictured in the first link mj1angier posted. I believe there is another way to do it without the additional level control pipe(see attached .bmp). The pipe thru the berm is set level at the high water point. The inflow is angled downward to midwater to avoid being clogged with floating debris. The end of the infeed pipe is the lowwater point. As the pond fills, the water rises in the pipe untill the water is high enough to start flowing thru the pipe and down the outflow. This flow will be self regulating to a point as the level rises, more water will flow. If the pond supply exceeds the pipe outflow, the level will raise above the top of the pipe and at some point the falling water will pull the remaining air out of the pipe and start a siphon. The siphon will run till the water drops to the level of the end of the inflow pipe. Or you could drill an air bleed hole somewhere along the angled infeed pipe to set a higher level so the end of the pipe is never exposed to floating surface debris. As soon as the water level lowers to the bleed hole, the system sucks air and the siphon is broken and the water stops flowing. The larger pipe above the smaller is the backup spillway or repaired original 12" culvert. You could also put in a second siphon above the first in the same trench. This would double your capacity if the first one is not enough to deal with the pond supply.

As already suggested, I would not dig into the berm below the water level. I would lower the water level before digging, but this way you are only digging to the desired high water point so you shouldn't have to dig too deep into the berm or lower the water level too far. I would also make efforts to seal the water side of the berm wall wherever I dig with a grout type substance such as Bentonite to prevent water from starting along the path of the pipe trench untill the repackd soil completely forms to the pipe and seals around it.

Good luck