Ceadmin
The bentonite was mixed with water to be about the consistency of Campbells cream of mushroom soup. If it is too thick it clogs the cracks at the top, and I wanted it to flow down into all the gaps.
I did this repeatedly over the summer, giving it a week or two to dry out again between pourings.
It was quite a lot of work, and I have a very small pond. I'm not sure if this would work for a bigger pond, or one that was leaking from somewhere in the depths of the dam.
It might make it easier if you poke some shallow holes in the top of the dam with a big stick when the clay is still moist in the spring, and then use these as pour holes as the cracks develop.
I guess the size and depth of the holes would depend on how big the dam was and how high above the water table it is.
People say clay settles over a couple years, so maybe my dam would have sealed up on it's own over time. But the bentonite in the cracks can't hurt, and it did seem to help me in my situation. Even in my small dam I managed to pour in almost 2, 50 pound sacks of bentonite. That is quite a bit of air or water space to get stopped up.
Good luck.
