Naturally Sealing Ponds (test topic)

[Iain Bagnall]

Has anyone got any experience of naturally sealing ponds?
I don't want to use any sort of liner, and if possible would rather avoid the expense of bentonite.
I'm hoping puddling the existing clay will do the trick.
Anyone done this successfully or have made any mistakes that I can learn from?
Thanks,
Iain.

[josephine_thompson]

Hi there.
Yes! We have a lot fo clay on our land, once you dig down 15 inches or so its mostly clay. Ours filled up almost instantly and has held the water for weeks now. Try just digging a small hole where you want the pond to be and see if it fills up. However, it is in a slightly boggy area where we've put our pond and yours may be very different.....
Hope it works.
Josephine

[Iain Bagnall]

Thanks Jo, I did dig out a small pond last year and it has held water over the winter but it dried up in the summer. Let us know how yours fares in the lovely summer I'm sure we'll have this year :-)

[MattLepley]

Hi Iain, we have some experience of this at Silent Haven. We have tried naturally sealing our main pond by puddling. Different sources seem to give slightly different advice, but we find it is hard to do it without the clay cracking. There are a few tricks you need to employ. Obviously, first of all you need to try to get every last tiny stone out of the clay that you are using, as any stones can cause cracks, however small.
Then the method I researched was to apply 1mm or 2 mm layers, making sure each layer has dried before applying the next. It may be an ongoing long term process. One source recommended doing this until you have a ten inch thick clay liner. This of course will take a long time. We reached a couple of inches thick and then decided to plant the pond up with oxygenating plants. Before planting up, the water got very cloudy with unsettled clay, for some reason. It seems that about the time we planted up the cloudiness disappeared, I'm afraid I didn't keep proper track, so can't say whether the cloudiness settled 'naturally' or as a result of the oxygenating plants. This coming summer will be the first summer since we have added the most recent clay layers, so I will let you know what happens. It is potentially problematic using puddling in Devon as you are supposed to puddle when it is dry, ironically.
Did you know they used to 'puddle' the side of canals by driving sheep into them?

[Chris P]

One of the issues in the midlands at least was various burrowing insects mammals etc. burrowing through the newly puddled clay. Soot was used extensively in the mix as a deterrent.

[Iain Bagnall]

Thanks Matt and Chris,
Looks like more research and experimentation then. Some good info coming up here already though. I wouldn't have considered the importance of removing small stones and certainly not the problem of burrowing animals, but both make a lot of sense....

[MattLepley]

Hi folk
Chris that's really interesting about the soot. Perhaps not such an issue when the soil is heavy in clay anyway?
Well the main pond by the house at Silent Haven seems to be holding the water fairly well (in the recent dry period we had). The water has gone down but I think that's all due to evaporation.

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