Gabion wall in a pond?

I'm playing fantasy gardens again and my mind is buzzing around the possibilities of installing an (almost) all natural pool with a deep area for swimming following David Pagan Butler's concept with bubblers and planted areas (link to intro video for those who are not familiar with it: https://youtu.be/aNCPA5PQpGA). I would like to use bentonite clay as a liner, rather than buying in a plastic liner. There are a number of areas that I'm unsure of the feasibilty of. This drawing is a possible section through the side of the pool.
I'm thinking of using sheep wool as a barrier layer instead of buying a geotextile fabric. I should be able to get hold of this pretty easily locally, although applying it in a layer could be fun.
I understand that clay generally needs to have a slope of less than one in three to avoid slumping in a clay lined pond, but I think that it should be possible to tamp it in between a gabion and (in my case) the rock cavity, to give a vertical seal. I was proposing a fleece layer on the outside of the gabion to stop the clay from seeping in there too quickly. I was worried the gabion might sink into the clay or get unstable, so I'm thinking of tamping a layer of 'rotten rock' (which is a local crumbly volcanic rock that makes a great track surface) for the gabion to sit on: again with fleece under the rotten rock. I gather that fleece has been used to support roads through peat bogs in the Scottish highlands, so I'm hopeful if will help here too.
My questions are these:

Has anyone successfully installed a gabion underwater on a clay lining? Does my foundation scheme look reasonable?

I haven't done enough research yet on the mechanisms of pond clearing (I feel another book purchase coming on) but I'm wondering if there is any reason the wall between the swimming zone and the regeneration zone needs to be non porous? All David Pagan Butler's I've seen seem to be pretty solid.

I'm thinking of using simple direct solar bubblers that would only work during daylight, and am not sure if the fact they are not circulating at night would be a problem? Mains electricity is a bit far away from my proposed pond site, and I'd prefer not to have batteries.

Would the broken rock infill of the filter manifold area also allow a steeper gradient for the clay, like a loose gabion, or is the whole lot just going to end up seeping through and leaking?

Any other thoughts or suggestions?

Hey Nancy.. I like your idea, and design, and see no reason why it shouldn’t work. (I’m no expert though, my ponds are just.. ponds.) If anything, the only thing I might suggest is increasing your “rotten rock” footer size, as too much is better than not enough. Look into gravity walls/dams for reference. Best wishes to you in manifesting this dream!

Where is the heater going?

Hi John, I'm not proposing a heater!
I actually don't mind cool water but probably won't swim unless the weather is pretty warm - I'm looking for a more "wild swimming" experience, but at home. I'm expecting that rocks in the shallow areas will heat the water to a warm enough temperature for me. We have black volcanic rock locally and you can notice this heating effect in the sea after a sunny day. If the tide goes out in the afternoon, the water off the beach has a hot layer in it as it has been warmed by the sun, and this happens in the river too. The challenge will be to circulate the warmer water to the deeper areas of the pond.
David Pagan Butler suggests insulating the deeper area to reduce heat losses to the ground, but again I'm not going to bother. With a clay liner that would be far too complex.

We created a soft landing for kayaks and canoes on a local river to prevent bank erosion. We created a thin gabion grate 4 inches thick 18ft x 18ft.  We were able to fill the grate from the top with river rock and rake it into the grate it solved our bank erosion issues. So it would probably work for your pond. With river run off we do get some rock loss but that wouldn't be an issue with a relatively static pond.  The round river rock is barefoot friendly. The bubbler within the gabion or under it  might create a biological filter with the surface area of the rock being the medium

I like it. Don't see why it wouldn't work.

Nancy  
This is a great concept and one that I have been researching since I too came across David Pagans utube page.
I am in the process of a gabion retaining wall,  my family is wanting a pool thus how I found David.

Have found much more information concerning using gabion as a retaining wall in this way?
the comment from Robert made sense and for me fortified my thinking that I was in the right direction as it would be a "relatively static pond"

If you have the time to post pics of the project and or have come across any more information concerning this plan I would very much like to see and read.

Thank you
Respectfully
Lance

Hi Lance welcome to Permies! Sorry I just saw your post....

I never got any further than the thought experiment, although like yourself think it ought to work. Gabions are certainly used as retaining walls for ponds and streams as an internet search quickly turns up lots of images. Here's a pretty pond in Surrey UK for example:

source

I think the installation difficulty will depend on your sub soil type - sandy, rocky, clayey. Mine is solid basalt rock and the thought of actually digging that out put me off. I've also now been given a Polytunnel which will be going too close to where my imaginary pond might have gone. The only other thing to consider is the gabion mesh material - stainless steel is expensive, but worth it for a durable result.

Gabion walls are used pretty successfully in waterways and coastal protection, but that probably depends on the infill rocks too. You can probably get away with smaller stones on the inside with bigger ones against the basket walls.

Good luck with your project - please let us know how it works out!

I realize it is a moot point now that you have a polytunnel instead of a potential pond, but if you have to dig into basalt rock for some part of a pond, it would seem that would be a sturdy edge for the deep area by itself. Even if the rock is fractured near the surface, I would think it would hold water pretty well, and applying clay to crevices would plug those if water wanted to seep into them.