We are located in a temperate continental climate with plenty of rainfall, although the summers can get a little dry with up to 40-50 days without rain.
We're planning to dig up a couple of ponds and connect them via swales for some much needed water retention. The challenge is that the soil is quite sandy and I doubt that we will be able to keep the water in the pond without it draining away. There is no clay on site and transporting it from off the property in the large quantities that we need is not feasible.
It looks like the best bet is to get some EPDM foil/liner, but I wanted to check in if there were any other ideas on how to handle this. EPDM seems OK, but can get pricey and I never feel too comfortable "isolating" an element from it's surroundings via hard barriers.
Hi Aleksander. I had pretty good success sealing my pond area without clay using pigs. I started a thread about it here if you'd like to read about it. It's basically the gley or glei method of sealing a pond, which I first read about here at permies in this thread.
"Instead of Pay It Forward I prefer Plant It Forward" ~Howard Story / "God has cared for these trees, saved them from drought, disease, avalanches, and a thousand tempests and floods. But he cannot save them from fools." ~John Muir
Personally I would only use a liner in a small decorative garden pond, never in a large pond or basin. The liners are so expensive, heavy and hard to handle, and could potentially cause a horrible mess as wayne points out.
One problem a lot of people make is using the wrong equipment to initially build the pond. Today contractors LOVE excavators, but for pond building they are NOT the machine. You want a bulldozer because it makes a very smooth, compacted bowl shape that helps seal in the water. I am not sure it would help with sand though, that is a tough situation to overcome.