Thx everyone for the replies....I'm new here so I don't really know how to tag members when I reply.
The clay hardpan is damp when first exposed, but will dry to near concrete hardness after about a day of full sun exposure....its challenging to dig, but holds water extremely well....down side is that it makes terribly muddy water which to prevent requires about 15 inches of sand to be brought back in to cover the clay before the pond can be filled.
As for filling the pond, there are no natural creeks, so it will be just rain and well feld. I am having a large irrigation well dug that will put out 500gpm....once filled it should only need to be topped off a couple times a year.
I grow bamboo and will have a large are of it around the pond ....so the well is for that too and the bamboo will grow over the displaced dirt when all done.
