"John Arruda" wrote:

Hello John

JA I am currently building a pond (still digging). I have large
JA boulders that go 2 ft below water and come 4 ft out of the
JA water. Theyre about 10 ton or so. I would like to have the
JA liner below the water line and glue it or silicone it to the
JA large boulders making it waterproof. I really dont want to
JA show the liner above the water and stacking stones on the
JA liner and boulder would be very difficult since it's almost
JA vertical. Has anyone come across this dilemma?? I see many
JA pond pictures on the internet with similar setups but they
JA dont tell how the liner is hidden.

Ick. I'm pretty sure that your bond will be very hard to do. Maybe,
just maybe, hot tar painted around the granite in a 10" or so strip
would allow you to adhere the butyl to, but any movement in the liner
(and they do move) is going to push that joint very hard.

Other such effects, I think, are done by fitting the boulder after
it's been lined, or using clay puddling which will make a fairly good
seal as it expands. Concrete is a bugger to seal to stones
effectively, though it can be done; but not well enough to trust
completely. (Use PVA in the mix, pva on the granite, two coats of pva
once concrete has set, and then brush all over with cement slurry
(also with pva). I've done this and it works, but only in small
ponds.)

--
Simon Avery, Dartmoor, UK Ý http://www.digdilem.org/