Thanks Ken. The strange thing is when I drained the pond and finally got a good look at the bottom, there wasn't much sediment at all. I pulled the excavator down in it and it only sunk maybe 2 inches.

I think my grandfather actually only made this pond as deep as it was. so, I dug a good 2.5 to 3 ft out of most of it and it was all solid clay. i didn't think I shoudl push my luck and go any deeper than that.