# leaking pond



## imalt (Apr 17, 2008)

My dads pond will not hold water. Its a 1/2 acre pond about 25 foot deep. It will only hold about 5 feet of water. It fills up in the rain and then quickly drains. My question is I have access to clay if I get a dump truck and just start dumping the clay down the sides and smoothing it out would that work.


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## [email protected] (Dec 22, 2006)

It should be lined with at least 1' minimum of good clay and compacted. 

The leak could be in the bottom and it's holding at 5' just because that's where the water table is or there may be a leak somewhere just above where it stabilizes. 

Getting 800 CU.YD. of clay spread around isn't easy and compacting may prove to be challenge as well. 25' is pretty deep for a 1/2 acre pond. If it's 150'x150' square, that means that the banks slope at 3:1 to a center point of 25'. If it's more rectangular or is square with one end deeper, that means that the banks are even steeper. Usually compaction is done with a dozer pulling a sheepsfoot but 3:1 slopes and greater can be tough with this method. They do have jumping jack style compactors that are mounted to an excavator but your limited by the reach of excavator and where it can sit.

Given the costs of equipment, fuel prices and the logistics and size of the pond, a liner may be worth looking into.

Some use bentonite clay to amend existing soil. Even this needs to be tilled in and compacted for best results.


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## imalt (Apr 17, 2008)

no luck on the bentonite I tried that. there is a lot of rock in the soil do you know approximatley what the cost of a liner would be. I said when the guy dug the pond it was too deep it drops pretty dramatically from the sides I would guess more than a 45degree angle from the sides to the bottom


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## [email protected] (Dec 22, 2006)

Prices on liners vary as much as car prices. Lot's of types, styles, options and substrate preparation recommendations (some need underlayment, some need to be used over very smooth dirt, some aren't strong enough to hang onto steep slopes etc.) Some are very UV resistant others are not. There are various grades/thicknesses available too.

As with most things it's probably best to use an established pro that backs their work up with a solid warranty. If you do it yourself do the research to see what will work best for you. Outside of choosing the material itself, some are prefabbed to the size you need but may be too heavy for you to install or shipping can be an issue. Some have difficult seaming systems or require special equipment join.

Some now have a trap door type valve in the bottom and can even be laid over an existing partially filled pond and will sink to the bottom. This can also help eleviate problems with water pressure from beneath the liner causing the liner to lift off the bottom or where groundwater infiltration make pumping impractical.


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## imalt (Apr 17, 2008)

I think the liner might be too pricey for me right now. I might try to back fill with clay 2 feet above the water line and see if that makes a difference and hopefully I get luck and the leak is under the clay at that point and sealed. Any thoughts on that idea. Is it just a waste of time to try?


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## [email protected] (Dec 22, 2006)

Maybe lowering the water level a few feet from where it's holding then covering exposed with clay. It really should be compacted as much as possible. It's possible there a vein somewhere in the side that it's leaking from.


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## Doboy (Oct 13, 2008)

[email protected] said:


> Maybe lowering the water level a few feet from where it's holding then covering exposed with clay. It really should be compacted as much as possible. It's possible there a vein somewhere in the side that it's leaking from.


YEP! What you said,,, Right-on.

' Dug many a borrow pit in my days, up around Cortland,, nothing but clay and blue gumbo on top of sand then shale.
Hit sand and shale in the bottom of quite a few.
To seal the bottom AFTER THE FACT, I just threw, with an excavator, buckets full of clay around the sides, above the water level. It my take a year or two of fills and drains, but, with luck, the clay melts down and seals the bottom. UNLESS you have a shale seam that's just tooo large. Then you'll have to pump it completely out, let it somewhat dry and compact the bottom with a layer of clay.
Ever see a pot hole in a gravel road, THAT WILL NOT GO AWAY? Just the opposite!
GOOD LUCK


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## WLAngler (Aug 29, 2010)

I believe this is the same problem my step-dad's pond has, sounds like he needs clay to fix it.


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## imalt (Apr 17, 2008)

the pond is still not full, but I dont know if the ground is that saturated or what but the pond has managed to stay about 1/2 full. I am waiting to see what it does over the summer before I pump it out and start over. One problem is I think when the last guy that worked on it took away the drainage to it. The water now drains away from the pond instead of in it. I put on my waders and walked out about 1/2 way the bottom has a lot of mud in it now. Maybe 4" deep or so. so I dont know if all the rain washed the dirt around and sealed some of the cracks or what.


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## [email protected] (Dec 22, 2006)

Site unseen, it still sounds like it's fluctuating with the water table which reinforces the sand/gravel vein theory. It should be full or nearly full given the weather this year. As far as the tile goes, a pond this size should have at least 6 acres of watershed feeding it and even with 6 acres feeding it will likely still fluctuate a few feet throughout the year. You should consider contacting your county soil and water dept. and see if they can help. A site visit is usually free and they may be able to provide some useful insight Normal evaporation would be 1/4" average per day up to 1.5" when it's really hot/dry/and windy. Clay expands when it's wet and seals better...when it dries, it shrinks and cracks can form so early would August would be a good time to make the repairs as the water should be at the low for the season and we usually get some good rains the second half of August.


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