We installed small rebar cages within each concrete pier for added structural stability. This will be critical support when considering the load of the deck that bears on only 4 of the concrete piers. There are another 8 more of these holes at the beach area for a smaller 20' x 12' "L" shaped dock. The 20' section runs along the edge of the sand beach and the 12' "L" section turns away at 90 degrees into a quick drop-off that will put it in 6 - 7 ft of water. A great place to tie up the Liberty Ferry when visiting the beach.