Pond Boss Forums INTRO Questions & Observations What pier diameter for dock

I'm hoping to use some Sonotubes to pour some concrete piers for my dock and was wondering what diameter they ought to be? I'd like to pour this myself without having a concrete truck come in, I have a pretty good mixer, so I'm hoping to not go overboard on the diameter. The dock would be a simple rectangle, about 15' X 6', nothing fancy. The deepest piers would be about 10' to the mud line.

A relative of mine was telling me that the ice on the lake development he lives on sheared his concrete piers off at the water line a couple of winters ago. He said it was because of the diameter but I'm not sure what he said they were. I also don't know if he used any reinforcement or if it would have made any difference even if he had, if the diameter was too small anyway.

We don't get a lot of long term freezes in the winter here but we occasionally get an arctic blast that might last a couple of weeks.

Also, for reinforcement should I use wire or rebar?

Thanks!

As for size, I haven't got a clue. But, for reinforcement, use rebar. See if you can find someone to make a couple of circles of #3 or #4 rebar (I'd space them 2' to 2 1/2' apart vertically) and tie in #4's or #5's insice of the circles.

Since concrete is porous, I'd look into getting the rebar epoxy coated to protect against them rusting and breaking apart the concrete.

You got a vibrator to make sure that there aren't any voids in the concrete once it's poured into the tubes? How were you planning on attaching the actual pier to the concrete tubes?

I'll be renting a vibrator. As far as attachments, I've never used brackets before, I've always just used j-bolts. I have no objection to brackets but I don't see it doing much for me and it seems like just one more thing to rust out. I was just figuring on a single j-bolt per pier, centered, then I'd just bolt a treated 4X4 or 6X6 to the top, letting the end extend just past the last pier so I can attach the end board directly to the wood, then string joists between them.

My builder recommended some outrageous size of pier because he said a tornado picked up his dock and threw it to the other size of the pond which, for some reason, he blamed on under sized piers. Not sure a dock can be made tornado proof! Apparently, his was really built up, he said it even had a wet bar!

5 ac of frozen winter pond, no issues to date

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.

Wow, Brettski! Awesome documentation of your pond project. Thank you!

Great info, Bullhead! I had some thoughts along the same lines as what you ended up doing. Now I'm thinking of going that route too since it seems to be working so well for you. It sure would simplify things. How long ago did you put those in? I'm glad you mentioned it was a 15 acre pond, like you say, that sure put it through the test.