# Pond Drainage Pipe Has Collapsed...help!



## Mushijobah

Hi All,

A property that I help the landowner manage has a nice .5 acre pond on it, spring fed. The pond is very old, and has seen better days in terms of its stage of succession. Even more alarming, the pond drain, a very old 6" metal pipe that runs through the dam and into a wetland below, has ruptured/collapsed/rusted. The water now trickles through the dam. Fortunately the pond never really gets flooded since it it fed by groundwater. The trickle is constant.

Anyways, I need to help this landowner fix the problem. I was thinking about digging a trench in the dam and removing the ruptured pipe and replacing it with some sort of heavy gauge plastic pipe. I'm guessing PVC would be too weak, could be wrong. I was then planning to refill the trench and seal around the new pipe with bentonite. Does my plan sound crazy to you? Any recommendations? I plan on renting a small backhoe from a tool company here and columbus. Am I crazy? Should I be having a professional do this? The landowner is not too concerned about looks, as the pond is at the back of his forested property. He just wants the drainage replaced. Would I be better off making a concrete spillway of some sort, or is that a pain in the butt?

Thanks guys.
Kyle

Here's a pic of the drainage pipe.


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## Snakecharmer

Check out some schedule 40 sewer pipe. Should be able to get it at Lowe's / Home Depot


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## Mushijobah

Thanks Snake.

Anyone ever use a spillway type like this?


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## bountyhunter

you might price a contractor [get one that knows this kind of work, some one who builds ponds. can,t hurt you could pick up alot of idea,s


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## hang_loose

Why not have the overflow pipe just below where the air vent (won't need the air vent) is on your pic? Then have the drain pipe tilted down farther at the discharge end.


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## [email protected]

Mush, your siphon design is missing some key features. The outlet needs to be lower than the amount it will be lifting and there needs to be an elbow at the bottom to create an air lock. A 3-4" siphon will move a lot more water than a 6" drain...usually are made from pvc glued. There needs to be a small weep hole in the elbow at the bottom to prevent the standing water from freezine and damaging it. They're kind of a lot of trouble if overflow only is the primary purpose. They inlets and outlets need to be securely stabilized as they can bounce around when cycling on/off. Freezing of the pond can damage in intake side and the vents, weepholes, elbows and smaller diameter pipes can clog easier. 










To replace the existing, I would recommend double wall, smooth I/S corrugated black plastic pipe with an antiweep collar embedded in clay. With a weep collar you really don't need to go with bentonite (clay cat litter) unless the soils are pervious. Just pack the clay on site around the collar well. I'd probably use a trencher instead of an excavator. I'd lower the pond first too...siphoning down if you have enough fall nearby or through the existing collapsed pipe. Check with ADS in London, OH for material details.

edit: I just realized that your illustration is probably more of a bottom draw overflow structure and not really a siphon system. This is draw off low O2 water. The vent is to prevent a siphon from starting. It would be better if it went clear to the bottom of the pond rather than halfway...which is why I didn't recognize it earlier. It should probably be the same diameter as the existing overflow pipe if has been sufficient. An antiseep collar wouldn't hurt in this case either.


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## Mushijobah

Thats guys!

[email protected]: How deep can those walk behind style trenchers dig? Also, if I use the anti-weep collar technique to just replace the existing drain, should I have any special type of outflow structure? Or can it just be a horizontal pipe like there was originally?

I'll probably need to remove most of the old outflow structure either way to prevent it from leaking. Might have to go with a small backhoe for that...unless it can be done with a trencher?


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## [email protected]

The 6" width walk behinds usually go 3' deep. They run like $150/day plus delivery. I'd call a trencher guy...you might be surprised at how cheap they are. If you're replacing what's there now (improving the seal at the pond to pipe transition with a weep collar) and the existing outflow has been OK I don't think I would change it.

Without actually seeing the site...
After lowering the pond, my first option would be to replace in kind: trench a few feet beside the existing and installing better materials. Dig out a few feet of the Existing pipe, plug the pipe and pack in clay where the existing few feet of pipe was removed. 

A lot of times, if you assemble the pipe, the trench guy will roll it in and backfill it for you. You might be surprised at how cheap this can be...assuming there's no underground obstructions or utilities involved. Here's a website I found with essentially what I'm talking about...it also illustrates why I wouldn't us an excavator in place if a trencher...http://www.libertynaturepreserve.com/p40.htm

By the way, I've lowered my pond a couple of feet by submerging a piece of 2" sandblasting hose about 20' long, capping the end then shoving it down my overflow pipe then uncapping to create a siphon. It took about 12 hours if I remember correctly think to drop my pond...an no fuel or equipment cost...I'd loan you the hose if you think you have enough fall. That 2" siphon created so much suction that I couldn't pull it off my waders when it leached onto me...I had to pull the hose out of the pipe breaking the siphon to get it off.


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## Mushijobah

Thanks for the tip, [email protected] I'll keep updating this one.


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## [email protected]

If you're adding up materials, you might want to figure in some sort of critter guard. 

Tips: The smooth double wall comes in 10' or 20' I think. If you have far to go, single wall buried 3' deep if fine. Use the double wall stuff where it could be run over/fallen on by trees or will be protruding/exposed. The sections go together with couplers that are zip-tied usually. I wrap up the seams in electrical tape to they don't seep. 

ADS is about as good as it gets....pretty lucky to have them so close. 

I had a trenching company come in for high voltage about 500' back to my house like 4' deep and I think it was under $400...10 years ago anyway. It only took them a couple of hours and they backfilled too.


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