Thanks for the update!
I would highly recommend putting a cheater pipe on your big wrench while you still have ice on the pond. You and a couple of teenagers on a 6-8' cheater could put significantly more torque on your pipes. (You might even have to use a little "feel". I suspect three guys on the cheater could actually twist off one of your augers on the bottom if it is sufficiently stuck.)
The other bit of advice is to put a cap on your pipes and have someone tapping with a baby sledge hammer while you are turning the pipe. A little downward "shock" force will also help you make depth in the clay.
