The bridge is small, just 6 ft x 16 ft. It will span a culvert drainage inlet that feeds the pond. I'm digging four holes (maybe 6 to accommodate a middle support beam) by hand with a clamshell post hole digger and I have 8 in diameter cardboard tubes. I am close enough to the pond that I hit water about 1 ft below ground. I can dig the mud out of the hole to a total depth of about 32 inches. The base of the hole seems relatively solid. I had thought I might drive rebar into the holes as deep as possible before pouring.
