okay I found a 2 inch hole where water was leaking out, so when it dried up yesterday I went to dig it up and patch it up. What I found was not good, I think. There seems to be a bed of shale. It starts in the deepest end and goes toward the shore so it gets deeper in the soil quickly as the bottom is very slopped. I dug up and keeping hitting bolders of shale. I did find between two of them a cave where the water was running out as it was real smooth clay in between them. My question is what is the best way to fix this. Do I try to dig out this rock to a certain depth and then pack clay in there. Or can I not dig it out..plug hole with clay and bene and just pack clay on top of rock where ever it extends ( if so how deep would the clay have to be? Do I try covering the are with a rubber liner and then packing clay on it? Or is there something else to try. Any help would be apprecitated.

Shale is tricky for getting a pond to hold water. My uncle recently built one and put a truck load of bene in it and he still had to wait for slit to naturally cover it up. This pond slowly leaked for nearly two years but it has stopped with the slit.