[Neil2]

First - dig the holes. I used a hand held post hole digger to go down about 4ft. The last foot was tough going and I rented an electric jackhammer with a long bit to loosen it up. This "pile" system would also work if you are worried about getting below the frost zone in clay clay-till soils. Next I supported a couple of 3/8 re bar in the holes and pored in concrete. The part that will be underground does not need the carboard tube forms (unless the soil is really granular or sandy and keeps caving in). The carboard tube forms are readily available at your local lumber yard or builders supply. After pouring the tubes, I bent the rebar and formed up a 5/8 in plywood platform to support the 4in structural slab pour. The last photo show it ready for the concrete. The circular shape is achived uisng strips of lighweight pegboard lined with tech tape curved against blocks screwed to the plywood. The ash drop opening is formed with a peice of 4in pcv pipe wired down. Note: always try to use round shapes, avoid square "inside corners", for openings in structural slabs.