10m² Pond without liner

I am building a pond in our garden to support our food forest by catching water, creating microclimates, growing food and fertilizer, maybe for having some fish and as habitat for all kinds of useful wildlife like frogs etc.
Due to legal restrictions it has to be 10m² or less and I want it to be sealed by just compacting the soil (contains lots of clay). As a fishpond in Germany (Zone 7a here) should be at least 80cm deep (close to 3 ft...) it is difficult to keep the balance between depth and not building to steep slopes. This is what it looks right now:



Work in progress, I just reached the depth of 85cm. I will have to build the dam at least 20cm higher to leave some freeboard. The "steps" must be flatened and I am thinking of some chinampa-like fingers on the right where the dam is yet to be closed. Another perspective:



The pond is located at the lower end of our property (750m², 1/5 acre) south of the food forest. It hast to be filled only by rainwater so it is placed to catch the overflow of a series of swales:



View from the northern corner of the food forest, top swale filled with leaves overflowing on the left into the diagon-swale that is overflowing on the right into the lowest swale which is overflowing on the left and into the pond.



Another view, diagon-swale, low swale. Picture from before the pond was dug.

We are also collecting rainwater from the roof of our house (we do not live there, just a garden with a small wooden house...) 300l each tank



and the overfow goes to a stone catchment below the house (about 500 litres)



I added a mud-playground for our 4 year old daughter and the overflow (from the catchment and the playground) is directed into another swale that ends



also in the pond. The pictures have been taken during construction between june 2016 (roof water collection) and yesterday (reaching ~3ft depth).

Tasks to be done:
- Building the dam about 1ft higher
- closing it (with or without fingers)
- remove stairs and corners from the pond and refill clay to seal it
- stabilize and design the outline with stones and plant ground cover and water plants
- a lot of things I will discover I have to do that I am not aware of right now...

Problems:
- I am building the whole thing alone (1 Person) by hand
- there seem to be more stones than dirt in my soil
- I am the only one to believe it will ever fill and hold water (I am sure it will but not yet sure how to seal it - compact by handtools, try to find some helping animals)

Has anyone ever tried to attract wild ducks to make them seal a pond? Sounds like a very permaculture kind of idea but...anyone?

Looks really nice.  Sorry, never tried attracting ducks!

I have a couple of "ponds" I dug on my property that only hold water for a few days at the most (after much rain).
I decided to call them "deep swales"  instead of "ponds".  

Only dug or also compacted in any way? I would like to hear someone say something like "I did it and it worked". I am pretty sure it can be done (or will seal it self if I have the patience to wait) and I am also pretty sure it will will fill even if it is leaking but as I said: No one else believes in my plans as I seem to be the only permaculture person around..

Those ponds were hand dug by me, and the soil has little clay.  
Also I found bedrock less than a meter down, so it wasn't worth doing much more work or spending money.

I am experimenting with growing clover and other vegetation in these depressions to see if the yearly dead layer of plants will eventually seal them somewhat.

I read about gleying a pond with organic matter. As far as I could find out it needs compressed ground, a layer of om about 1ft thick that is covered by a layer of clay to start an anaerobic process. I was thinking about that but it would need me to dig another 1,5 ft deeper and I am close to never dig again after tons of rocks...

Update: some throwbacks....

There actually are more stones than dirt in my soil! When trying to remove some stones to be able to compact the ground I only found more stones (repeated a few times...). I had to remove about 20 cm all around the deepest zone which caused the slope to become nearly vertical. When trying to refill those 20 cm to create a structure that can be compacted I put the dirt/stone ratio to the test:



So I am running out of material like 50% of all pond/dam projects..

More problems: The dam felt like rubber after compacting. It has no core as I thought such a small dam could just be build on the ground. Not sure if that would have become a problem but it became the solution for problem number 1! I took the material from the dam to build the pond (actually to build and seal the lowest 20cm).



Water depth is about 15cm (1/2 ft) and it is holding water pretty well so far. A friend of mine has some clay left (after building a house) that I can use to build that ring high enough to cover the stones on the left. Then I will be able to seal the pond all the way up (and rebuild the slope less steep!).

That clay will also be used for the dam that will get a core before building it up to the planned height. I am really exited to see if the pond still holds some water on friday...

I haven't started my pond yet, so I have nothing to add there, but anyone that makes a mud playground for their daughter sounds like a great Dad.  

I have to admit that it has been the idea of a great mom...but thanks!

I did the same, hand dug and no seal two areas.
One is still filled with water even on hot days, the soil is clay with some rock and the ducks poop-sealed it.
The other one is dug in a mix of clay and more sandy rocky soil and that one is empty now with only the clay areas ponding.
Your soil looks very porous and also it looks consistent, maybe you don't have clay anywhere on your land, if you do maybe that'll do the trick but one thing I noticed when probing the poop-sealed pond is its depth had already diminished, from water flowing in and also duck-sealant.

Laurent Voulzy wrote:
Your soil looks very porous and also it looks consistent, maybe you don't have clay anywhere on your land

depends on where you get the soil. The mix in the pond is very random and what you see on the slopes is different from what I used to seal the botton. But as I "import" soil instead of just digging and compacting I am going to test the soil. The hill our house ist standing on was build from the basement excavation and that is clay. Maybe I am going to use some of that..

Torsten Frary wrote:

Laurent Voulzy wrote:
Your soil looks very porous and also it looks consistent, maybe you don't have clay anywhere on your land

depends on where you get the soil. The mix in the pond is very random and what you see on the slopes is different from what I used to seal the botton. But as I "import" soil instead of just digging and compacting I am going to test the soil. The hill our house ist standing on was build from the basement excavation and that is clay. Maybe I am going to use some of that..

Cool, it's always a bonus to know your land On a side note I'd advise to dig 2x as deep as you intend because of the deposit that occurs with time.

I know and I would really dig deeper but a pond on my property is limited to 10 m² and it is already adventurous to have it 80cm deep within 4x2,5m. Maybe I forgot to mention: It is not going to hold fish any more, so it does not have to be or stay really deep. When scouting youtube I see a lot of people build huge ponds and I would really love to have one too, but this one is the maximum I can do here.
Maybe the willow (that I planted before planning the pond) has to be replaced to limit the amount of leaves in the pond...

I also made a pond or deep swale without liner. I started last summer, it was a heavy job, because the dirt was very dry and compacted. Some layers were almost pure clay. Also a lot of stones, lucky for me only small and medium sized ones. The pond is on my highest terrace, connected with a big swale that catches most of the rainwater that runs off the slope. Its deep, about 2.5 metre, but very small, only about 2x3m on surface level. I wanted to make it as deep as possible so evaporation would be less. The pond fills up quick after substantial rain, in the winter it was completely filled. But last months were very dry here, so now its almost empty. But I already noticed one thing; one of my orange trees didn't give much, but now its full of flowers! The tree stands down slope from the pond, so it seems the tree is already taking advantage of more water in the soil! I am planning on buying a small waterpump, so I could fill the pond in spring and summer from my well. But I guess right now that would not be smart, because the waterlevel in my well is already low, and the dry and hot summer has not even started yet.

Did you use all the water or is it leaking? How did you manage to seal that big hole?

My pond seems to be sealable with the material I have (quality not quantity...):



Todays picture after 24 hours and not more than 10l of rain (6-7mm plus very little amount of runoff). This small part of the pond seems to be sealed extremely well considering the small amount of clay and effort used. I am pretty confident this pond can be sealed with clay only and I now understand how it can be done!
Some work to do on Friday and Saturday and some patience until it fills up by rain (my brother drives a Dakota and is able to bring serious amounts of water if I run out of patience...).

Pond is still holding water and I started rebuilding the dam:



The clay layer on top has been used to shape the pond. The trench is about 20cm deep into the original ground level and I rescued some very good top soil from beeing buried:



I am going to dig the trench 2-3 m longer on the right to create a swamp zone, fill it with the clay from the bottom of the pond (my best clay) and compact it. My friend took a sample of the soil he has left and if it contains enough clay (lookin very good) we are going to get 1 m³, build up the dam, shape the inside of the pond and voila...

I got really deep into the whole thing and have the idea of building a dry wall from the stones I got. By cutting the slope on the left I could have another swamp zone instead:



A close look to the pond (holding 200 - 250l of water):



to be continued...

maybe this is mentioned already: bentonite

I read about it, but I do not want to buy stuff until I really need to. And it seems I will not have to:



This is a sample of the soil I can have 4 free after four hours in suspension. Not sure about the structure yet but I guess it is looking pretty good?

If the pond can not be sealed with clay I would prefer a rubber liner over bentonite because the latter is also not 100% sealing as far as I could find info about it (there is a great risk of doing it wrong...).

Sorry, but it seems I did not mix well enough. New Test:








been shaking for 15 Minutes, last picture was taken after 5 minutes rest.

Soil tests didn`t show usable results, anyway: Pond is holding water pretty good!



I am building a dry sone wall on the left to flatten the steep side of the pond. That is where I put lots of the stones I found and where I can get easily a ton of good clay. As I am running out of space for storing stones and different kinds of soil I have to take turns: Dig, sort stones, seal pond, transport soil elsewhere.
The pond is sealed mostly by puddling clay and compacting the soil as good as I can. It now holds about 500 litres of water and is 25 cm deep. If it holds the water for a few days I am going to seal the whole thing, build the dam on the right a lot higher and it should be good. Not sure about the levels and the exact design of the boundary yet but I can see the light at the end of the tunnel.
A closer look:

Any updates on your pond?

I was busy doing other Things in the Garden and am now waiting until all the leaves have fallen. Funny you are asking today, I just took a picture yesterday:




Clearly a fake, the pond did not fill up; I had to empty my rainwater tanks ant took the picture after filling 1500l into the Pond.

I hope to be able to start building the drystone wall in december and finish the Pond before spring but I might have to reshape the deepest area before I can do so.
Will keep you updated..

If you really wanted it deep you could dig it with vertical sides most of the way, but a shallow edge all round, think of a upside down top hat, with the soil tests, you need to wait 24hrs or so to have clay settle out, but I would say looking at the pictures you're going to need a liner, or cement or something to seal that. We have dug natural ponds here but it's not comparable as any hole here fills up within a week just from groundwater!

Skandi Rogers wrote:If you really wanted it deep you could dig it with vertical sides most of the way,

But wouldn't this steep sides be of a higher angle than the angle of repose and therefore be unable to be compacted and sealed?