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.