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 :2cents:

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... :thumbsup:

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.

 

[Localmotion]

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.

I really like the idea Gary... Have you tried it to make a pond, or is it just theory?

If anybody else has tried this (or similar), please let me know how you got on.... :thumbsup:

Also please can someone explain what Bentonite is??? I've never heard of it before - I live a sheltered life!!!

 

[sweettractors]

I have a 50 X 50 small decorative pond that I have tried Bentonite on and it did not work and cleaned it out with the dozer again with no luck and finally bought a $400 light liner and guess what, the deer poked holes in that. Today, I have a pond with no water. If I could find the leaky area I could fix it. I like the cement mixed in sand idea. Ken Sweet

 

[EddieWalker]

There are only two things you need to know about concrete. It will get hard, and it will crack. While swimming pools are good at dealing with this, it's not something that happens by accident, and the bigger you make the pool, the more effort it takes to make sure it won't crack on you. Even then, it happens. You must REALLY want a pond!!!!

Eddie

 

[Western]

To bad you cant use the Marble for the bottom, then you only have the walls to deal with. Even with small cracks in the Marble, that would be better than sand.

If you do go with a line for whatever reason, spend the $$ and get a 45mil.

You may be able to get more clay fill from any excavations going on around you to. I'd take clay over most anything.

 

[Localmotion]

You must REALLY want a pond!!!!

Eddie

Yup - coming from the UK and living in an area with no natural water courses, I am desperate to have a little oasis :laughing:

Also it'll give our ducks somewhere decent to swim - they're not impressed with the old baths they currently have !

I take your point with the concrete though - although would still like to hear if anybody has actually tried it.

Also I will try a dug out tomorrow and see how well the clay holds water.. it maybe that we can use a combination of clay & liner (belts & braces) approach?

 

[roygul]

I'm in the same situation. Currently Cleaning up a small dam/pond. Removing all the trees that have grown up around it.

http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0004/164038/leaking-dams.pdf

This document may be of use to you. Lists various methods of sealing them. Pro's and Cons.

Cheers
Byron

 

[boggen]

Pond Boss Magazine: Welcome and Koiphen.com would be other resources you can use. there both like TBN but are more geared towards ponds/lakes. vs tractors.

there are a variety of rubber like liners out there. from EPDM to PVC to (list is rather long) some are cheaper, while others are very costly. other examples of laying down a geo textile fabric and then having a company come in and spray down a rubber like liner onto the geo fabric. to create a custom shell.

remember there are many sewage ponds, and chemical ponds out there. besides backyard liner ponds, mud ponds, and lakes. that the various liners come from.

===========
most mud bottom ponds rely on "clay" or rather bentitite clay. but if you are looking at this. i would highly suggest to get a soil engineer involved. so they can take samples, and tell you what you need to add and amount of it. they might suggest different things.

also contact your local "fisheries" / "hatcheries" that breed fish for local lakes and ponds.

ponds have been around for years. meaning most libraries you can find old farm books, that give detailed info on how to build a pond. that still hold for most part true today. books generally also go into details about building run off areas and like to help trap silt before it makes it into the pond/lake.

 

[BruceWard]

Bentonite Bentonite - Wikipedia, the free encyclopedia

 

[Localmotion]

Thanks everyone for their help.... :thumbsup: especially Bruce for his link about Bentonite

I think we may be very very lucky - often when digging holes for customer swimming pools & depositos we hit a grey, almost shale like seam about 1-1.5 metres down. We've even hit it here on our own land, just before we get to the sand...

Having followed Bruces link and done a bit more research I think it may be Bentonite. Having looked at images of it in it's raw state, it looks identical, and checking the geological survey it would appear that our area of Spain does have deposits...

Also it seems to react in the same way - we had a customer a year or so back who asked us to spread the "shale" we had dug out of his pool to make a hard standing area - but after the first rain on it he wanted us back to take it up again as his car got stuck upto the axels in it! When wet this rock like substance just turns to jelly!!!

Does it sound like Bentonite to you?

Has anybody used Benotonite to line a pond?

Does anybody know the best way to prepare & mix raw bentonite (straight from the ground) to use as a pond liner?

Thanks again in advance for all your help :thumbsup:

 

[Localmotion]

Update:

Have just done a couple of bucket tests using what we think maybe Bentonite and also the light clay top layer that we have here....


2" layer of the light clay topsoil drained 5L in under 2 minutes, most of which was then present in the bootom bucket (so not much absorbtion).

Tried again, this time paddling 2" of the light clay first, but still drained after 30 minutes Have not bothered to try a scrape, as really don't now think this is an option. We do have some areas where the clay is a bit heavier, but definately not enough for this project.


2" layer of the Bentonite like material, crushed up drained only 3L of the 5L before stopping. Interestingly of the 3L drained, over half was absorbed and not present in the bottom bucket

With a 2" paddled layer of the Bentonite, nothing had drained after 30 minutes, and the top bucket was still full to the brim I have left the test set up and will check it later to see how much has drained, but hoping we may be on the right lines here... :thumbsup:


Assuming the bucket test still looks good later, our next trial will be to dig a small pool (probably about a cubic metre) and we'll try lining it to see how it works...

If anybody has any tips on working Bentonite from it's raw, rock like state right through to applying to a new pond, please let me know...