Sealing a pond with steep slopes without liner

[gautprod]

Hello everyone,

I’m currently working on a pond project and I’m facing a challenge. My pond is approximately 8x4 meters (26 X 13 feet) in size and almost 2 meters (79 inches) deep at the deepest end, average depth of about 80 centimeters (32 inches). I was planning to use sodium bentonite as a sealant but due to space constraints, the slopes of my pond are steeper than the max recommended 1:3 ratio (V:H) for using sodium bentonite as a sealant.

From what I’ve read, sodium bentonite is not a good option for me as it tends to creep downwards on steeper slopes. If I were to follow the recommended slope for bentonite, I would have to reduce the depth of my pond to just 67 centimeters (26 inches), which is not good since I live in a region where freezing temperatures are common, thus maintaining a deeper pond is crucial.

I came across a comment on YouTube suggesting to use 10-20% Portland cement mixed with clay or soil as an alternative method to seal ponds with steeper slopes. Has anyone here tried this method?

Please note that I’m not interested in using pond liners, ducks, or pigs for this project. Any other advice or suggestions regarding using natural materials to seal a pond with steep slopes are greatly appreciated!

 

[SparkyJones]

If it's a year round pond and you don't want fish kills in the summer or it ever frozen solid in the winter it will need to be 8-10 feet deep. More like 3 meters, not 2. Too shallow and in the summer when it evaporates off some you'll get massive algae blooms that will choke out life, at 8-10 feet, your deepest areas won't grow plants or algae and even if you burn off 1-2-3 feet in drought conditions in the summer it still will be deep enough to stop growth from occurring and in winter it should have a good amount of unfrozen areas of water under the ice even if starting low and extreme cold for prolong periods. You can plan for 6-12" of ice, but better to plan for 12-20" of ice for longevity of the pond.

If you have the ability to work your steep slopes while dry, you can mix the bentonite in with the side material to about a 10cm thickness/depth and pack/tamp it in so it won't slump when it's filled up.

Only thing I can think of if youre not wanting to use a liner or sealer besides the bentonite. the cement won't work, it's not water proof without being sealed so it's not going to work out.

 

[BPSabelhaus]

Water disappears quicker than you think Permanent water is permanent because water is flowing into it from the surface or from subsurface sources.

 

[gautprod]

Thank you for the replies. The pond is dry, I've just finished digging it. I have now been in contact with several distributors of bentonite and all of them say the same thing, sodium bentonite is not a good option for me as it tends to creep downwards on slopes steeper than a 1:3 ratio (V:H). Guess I'll need to look for another solution.