Update: Got all 25 holes down with a diesel tractor and a big 16 inch post hole digger on the 3-point hitch. Deepest on was just over 4 feet, and then we heard the cha-chunk cha-chunk that we heard at 2 to 3 feet on all the rest, as we hit the ledge. Alright!
Another Question: What's a good way to position the rebar prior to pouring?? I'm thinking tie wire through the side of the sonotube?? Any suggestions on this appreciated! And the L bolts: tie them in before pouring, to make sure they hook the rebar well?? Or insert after pouring?
Thanks for all the help. When I get this further along I'll put up some photos..