Best way to line a pond?

[Localmotion]

Hi all - need some advice about building a pond please....

We are looking to construct a small pond about 50 metres by 16 metres (164' x 53'). The land here is light clay topsoil, but only to a depth of about 2' afterwards it turns into sand / light stone before getting to marble at a depth of about 3 metres.

I've got no problem digging & landscaping the pond (having done it for customers before), but I really have no idea on the most cost effective way to line it?

Back in the UK I have seen expensive rubber liners used as well as puddled Clay. Here neither is really an option for us - the clay here is too light to puddle and we can't afford a liner of the size needed

I am thinking that we may be able to line the hole with sand, and use heavy duty plastic sheeting, maybe with a concrete rim around the water line to avoid any damage, However I don't know how we would join the plastic sheets to get the length & width we require

Any ideas please????

[EddieWalker]

How good is the clay top layer? Will it hold water? Can you set it aside, dig out the pond and then line it with the clay?

Liners have a limited life span. The bigger the liner, the more problems you will have with it. Liners are rubber because it's flexible and lasts longer then plastic. Plastic tends to break down in the elements fairly quickly, where most rubber materials last quite a bit longer. Both are bad ideas, one is just worse then the other.

Any chance that you can seel the sand? or trade it for sombody with clay?

Good luck, sand is just about the worse thing you could have found.

Eddie

[kidr]

Till in bentonite?

[EddieWalker]

Bentonite will expand when it gets wet, and sometimes helps with a leak in a clay pond. But not always, and never in just sand.

Two feet of decent clay is what is really needed, but getting it there is where things get a bit out of hand. Especially with the price of fuel out of control like it is.

Good luck,
Eddie

[Don87]

I suggest cutting your pond size in half, and using the rubber liner.

I put in a pond 7 years ago with a rubber liner and so far it is doing good.

Just be sure to get a 1 piece liner, as thick as you can get.

Liners that you need to glue sections together will seperate from water pressure with more than a 1 foot water depth............don't ask how I found this out.

Line with old carpeting, or something soft before installing rubber membrane to protect the liner.

A new liner can be installed over an old one, just pump the water from underneath, to the top..........you only lose a few Koi this way.

My pond is 19 feet by 22 feet and 3.5 feet deep. (depth is a necessity if you are going to have fish)

[Localmotion]

Thanks for thr feedback...

I agree with Eddie that if we can use the top clay it would be the best bet, but am concerned as it really isn't very good clay.

I might try forming an experimental dug out just about a foot deep, puddle the sides and see how long it holds water for - this should give me an indication as to whether or not the clay is good enough to be used???

To ship clay in isn't really an option for us here - we are on a small palin surrounded by mountains, so the soil here is about as good as it gets. The surrounding areas are all very rocky - infact many of the fields we plough have only 2-3" of shale under which is solid marble - don't ask me how the vines & olives manage to grow, but they do!

If we have to reduce the size of the pond and go for a rubber liner, then that is also an option - although we were hoping for a large body of water so the pond doen't need re-filling so often as water here is scarce.

As another thought - has anybody tried building a concrete pond? Perhaps a 2-3" scree would hold? What do you think????

[hr3]

Localmotion,, What is your water table in the area you are going to put the pond ?? and how are you going to keep it full of water even if it is lined?? The reason "I ask is I have about the same size pond clay lined but the level goes from the top drain to about 4' down in the dry season ???

[Gary Fowler]

You might try mixing cement with the existing sand to form a dry mixture and then pack it down like we use for road beds in some areas. It would take a lot of cement but would be cheaper than concrete. If you have a tiller, you could mix the cement and sand with that. Mix ratio would be something like 100 to 200 pounds of cement per cubic yard of sand. It might still be slightly porous but should set up similar to cement grout.

[Redneck in training]

How good is the clay top layer? Will it hold water? Can you set it aside, dig out the pond and then line it with the clay?

Liners have a limited life span. The bigger the liner, the more problems you will have with it. Liners are rubber because it's flexible and lasts longer then plastic. Plastic tends to break down in the elements fairly quickly, where most rubber materials last quite a bit longer. Both are bad ideas, one is just worse then the other.

Any chance that you can seal the sand? or trade it for somebody with clay?

Good luck, sand is just about the worse thing you could have found.

Eddie

Another bad thing about the liner is lack of mineral exchange. Liner turn the pond into a swimming pool that has to be monitored and chemistry of the water maintained.
Bentonite could work if installed properly. It needs a "back pressure" of at least a foot of some material compacted on the top. When it expands it fills all the crevices and seal it. Good compaction is the key. Without back pressure it gets washed off.

[Localmotion]

Localmotion,, What is your water table in the area you are going to put the pond ?? and how are you going to keep it full of water even if it is lined?? The reason "I ask is I have about the same size pond clay lined but the level goes from the top drain to about 4' down in the dry season ???

Water table is nearly non-existant here, although bizzarly we do actually have an underground salt water stream flowing accross our land!

We know that it will be an issue to keep full, hence why we want to go as large as we can afford. That said we are entitled to use the agricultural water here (delivered down channels from the mountain resivoirs), so we can always order a few hours of water if we need to top it up.