We've got a ranch that has a 20' tall concrete wall dam holding back about 1.5 acres of water. There is a small hole in the dam wall we are thinking of patching with Vandex Super made by Euclid. That's a really small hole so not much of an issue. There is a good amount of water leaking under the dam where i'm assuming the concrete dam meets rock in the ground. I'm considering throwing in a bunch of Bentonite on top of the water in that area and hoping it sinks down and expands to seal the hole. Is this what you guys would do? Would you drain the pond and try to wedge a lot of clay along the bottom of the dam? Is there another product to try? Thanks so much for any thoughts....