I used 8" PVC, jammed it down into the mud the best I could with a block of wood and a sledge. Then pounded rebar down as far as I could (maybe 3 feet) then filled them with concrete. My dock is a 4x12 walkway to a 12x12 square. So far it has held up against ice and waves. It is on a 15 acre pond, so I can get some pretty good sized waves. Haven't had a tornado there yet though.