I'm taking a break for a few before I go back out to check to see if the hole is now too deep, or not deep enough.
Once that's at the right depth, I can start piecing everything together.
I had gone out to get all this different material for the corners and intersections, and found that the best thing for all that is what I bought the fewest of.
I'm not returning the other stuff, because I might be able to use it elsewhere; even if just as thin spacer material.
I should say that I'm not going exactly by the book. My spaces between joists won't be 16 inches; more like 12. Of course, it's got to hold quite a bit of weight: the pond itself will be made from 4X6s and the water itself weighs quite a bit.