Concrete pond construction

[gautprod]

Hello fellow pond enthusiasts,

I'm in the process of constructing a pond and would love to get some advice from those with experience in concrete pond construction. The pond has been excavated, revealing a sloping bedrock at the bottom. The sides are steep, almost vertical, and part of the pond structure is above ground, reinforced externally with a thick layer of soil and stone.

I plan to use concrete blocks for the sides, but I want to maintain the natural slope of the bedrock. To do this, I'll need to create a level base or foundation around the sides on the bedrock before setting the blocks. What would be the best approach for building the foundation? Could a circular slab reinforced with rebar work? What would be the best waterproofing agent or coating to apply to the concrete to prevent water leakage and protect aquatic life from the alkali content of the cement?

I'm aiming for a durable and eco-friendly solution that ensures the health of the pond's ecosystem. Any tips, product recommendations, or construction techniques would be greatly appreciated. I know that it would be easier to just use a pond liner but I am optíng not to.

 

[Lakefish]

I really think you need to talk to a mason about it. Or several! Concrete is not so easy (as I found out).
Only useful thing I can tell you is that leaching won't be a problem in the longer term. It doesn't leach for too long. I have a small concrete pond, unsealed, with liner underneath "just in case" and pH is generally neutral. Maybe a little acidic at this time of year. There are shrimp and all kinds of aquatic larvae in there, not bothered at all.

 

[gautprod]

Thanks for the reply. I could drill into the bedrock. The problem is that it is on a rather steep slope, where at the shallow end it is only about 50 cm (20 inches) deep and at the deepest end it is almost 200 cm (80 inches). The bedrock is a great seal, it doesn't leak any water from there. The problem is the sides that consist of very porous soil. This is one of the reasons why I would prefer not to use a pond liner, it simply wouldn't be necessary for the bottom of the pond. I want to find a method to seal the sides without covering the bedrock.

I have seen some videos where they use shotcrete. I don't know much about it, but it looks like it could be a possible solution.

 

[Fishfur]

You’d need an experienced contractor that works with shotcrete - so much depends on the degree of slope and how stable it is to start with but it’s supposed to be a good solution for slopes from what I’ve read. I read about pond building periodically just in case zi win ygst big lottery one day.

I have an enduring fantasy where I’m living in something like a mansion and have a huge pond built that’s very deep and serves not only to house fish but as a natural swimming pool.

I occasionally dream about watching it be constructed .