I've been reading a lot of threads on here about building dams, keyways etc. but I have a unique situation on my ground. My land is reclaimed strip mine that was reclaimed about 50 years ago. The coal was about 40 feet deep and the overburden is all mixed together just as it came out of the shovel including lots of rock and some boulders as big as a Volkswagen. I know it can hold water because I have two ponds on the property and I am just assuming the dams were built as part of the reclamation process. One holds water very well and the other leaks like a sieve down to a certain level and stays there. I have a draw on the property that is well suited for another pond and I want to build a technical dog-training pond that will cover about 2 acres. A technical pond has lots of points, levees and maybe an island. I know it is probably a crap shoot when it comes to putting in a pond but I plan to buy a dozer for some other work and thought I would build it myself so I am only out the cost of fuel and my time if it doesn't work out. I could have good clay hauled in to build the keyway but there is no hardpan to tie it into so I could build a nice keyway and still have a leaking pond. Hauling in enough clay to line the whole pond would be too costly so I'm thinking just do it myself, use the materials available at the site and do the best job I can with my dozer and my Kubota M8200 with a loader and a heavy duty box blade on the back. Comments? Advice?