It really doses pay to network!
I've been talking about my pond issues at work and one of my co-workers just happened to finish digging a pond. He tells me he has a large amount of wet heavy clay, some in manageable chunks. He is willing to let me have some, all I have to do is move it.
It's going to be alot of heavy hand lifting, but this is my best shot at sealing the ledge.
I plan on packing the wet clay on the legde and then pouring a mix of bentonite and botton soil on top for good measure wish me luck!