Pond Boss Forums Thread Like Summary - Gravel Layer Below Clay Bed: Help Needed

I am having a dug and dammed pond excavated and the topsoil has been stripped. We have found gravel at various depths below a workable clay cap, the shallowest being 2-1/2 feet down, have not reached it in other areas. The comment is often made that 1 ft of good clay will be enough to seal a pond at 10' and we are not planning on going more than 8 or 9. My questions are

If we are careful about leaving a good 1' layer of clay and compact it with a sheep's foot roller, are we safe? Anything else we should be doing, or can do to ensure a good seal?

Thought this could be an issue in some of the core trench area. They ran a test hole 50' out and the gravel went down a ways. We dug about 10-12' down in one area and more gravel, but that area had 5' of clay. In the end they were able to get to clay through the 4' deep core trench. Don't know if there is gravel below but hope any gravel below will not be an issue. Good or bad assumption?

Any input would be appreciated.

Keep in mind the 1' layer is not "place 1' of clay and compact"... 3 of the 6-8" lifts each compacted under proper conditions will "bind" best and be in the 1 foot thick range when done-don't stop there-when your seal is completed in reference to depth, go back and place a blanket of 8-12" soil and lightly compact. This gives soil for several types of aquatic plants to root in without going too far into seal and it protects moisture content IN seal from drying out too fast if it doesn't fill as quick as you hope.
Any sand or gravel you could stockpile you can use to make gravel beds in what you believe will be 2-5' water. Say a few areas 12X30'.
I'd highly recommend you get in touch with TJ.. He's very good as this stuff.

Mike Otto, Bobs partner, and a pro pond builder in the PB Mag, once said something like “ Dirt leaks. Accept it.”.
We can mix it with clay to cut down on porosity but it’s always a crap shoot.