Dock foundations/piers on a lined pond

While I'd like to do a clay bottom pond, I'm at the top of sandstone hills working with a bermed pond situation - there's no way clay will work.   So I'm looking at EDPM liner for my ~50 foot diameter, ~7ft deep pond I've got mostly dug.

As I think about future plans, I know I'll be putting in some sort of deck/dock, and probably want it on the berm side - about 50% of the edge of this hole is berm, while the other half is the slope of a hill it's dug into.

I don't have the liner yet, and have a bit more tractor work to go, but I'm starting to think about how THE FOOTINGS of the deck should be placed.  I don't think I could do floating on one side, as there's a good potential for at least a foot or two of evaporation drop each year.  So, can people tell me how you've done your piers for lined ponds?   Concrete blocks UNDER the liner? On top of?  Just wood posts? posts with soft tips?

Firstly, have you seen some of the work on gleying a pond with pigs or an excavator so that you don't need a liner?  Might be worth checking out if you haven't.  Might even be able to do it with a tractor...

Secondly, I'm thinking you wouldn't want anything under the liner like blocks.  Then you'd be pinching the liner between the dock legs and the block.  My approach would be to have the bottom of the pond be level where the dock end will be and then put wide feet on the dock posts.  Say 2'x2' with curved up edges and corners.  Hopefully you'll have some sand or something on top of the liner and the pads of the dock legs can settle onto that sand.  Even if they get down to the liner it shouldn't puncture it.

Pig keeping is not in my future, for many reasons.   Also, this hole is mostly dug, and it's 50 feet in diameter, in mostly sandstone soil.  The berm - the artificial 'wall' of 50% of the hole is about 6 feet high, maybe 12 feet at the base.  


I agree with your assessment about not *pinching* the liner.   I'd still really like to hear how other people put the piers in their lined pond.