Brettski, you are thinking ahead! The only thing that I would have done differently was use larger washers under the head and nut on the carriage bolts. (4" x 4" x .187" C-1045 or so)I'm thinking you used grade 2 (unmarked) bolts, which have a tensile of around 20.6K pounds. I think they will pull thru the wood before they fail in tensile.

www.hoosierpondpros.com

[Linked Image from lh6.ggpht.com]
http://www.pondboss.com/subscribe.asp?c=4
3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).