Howdy Beaux! Fellow offshore worker here(supply boat captain). Your project sounds so similar to mine, with the complete opposite soil problems! My 15 acres is also combo woods and pasture, with the reverse soil issues. Good topsoil to 3 feet then solid clay to the earths core! I had no problems with the pond holding water, but my septic system for our home became a major issue when the home was built. Of course it was nothing $$$ could'nt fix. I'm posting this because all of my focus was on the pond and not on the home. It sounds like you should have no problem with your septic from what I have read about your soil conditions on your post.
Glad to hear that you found a source for some clay right on your property to line the ponds with. Although my pond and dam had a good clay bottom and core, I still had a little bit of leakage through the dam in one spot. It was a compaction issue. The pond was dug with a dozer and that is also what was used to compact the dam and pond bottom. Consider compacting your pond bottom with a sheeps foot roller to maximize the compaction and avoid a leaking pond. The dozer or excavator tracks will not give you nearly the results because of the area they distribute the weight over.
We just started living on our place a few weeks ago and I gotta tell ya, get ready to live the good life! Keep the updates coming and good luck with the entire project!
