Quote:
Originally posted by Robinson:
I appreciate all the advanced science of soils, believe me, but see nobody saying, some clay breaks down a bit, when submerged, and blend with other soils, making them more clayish, hence making these blended soils, in combination, tend to seal.

I've heard of ponds filling two or three times and leaking all the way down before a seal is made. I do think Bill has the right answer though, don't trust your pond to time driven sealing. Compact it down with good clay and seal it yourself.

Interesting thread.
Great point Robinson, we've just been speaking in "endmember" terms......in practice, I would strongly recommend blending any pure clay with native soils (unless of course yer lucky enough to have a mile of clay like brettski does). For myself and probably most other folks though they have inadequate native soils and need to help them. Installing a pure clay layer can lead to similar bad issues as installing an artificial liner particularly if its installed dry and/or not thick enough (water will "communicate" through it and seep out) and also if pond drys below certain point clay will shrink and crack and not heel properly when re-wetted. By blending with native (coarser) materials but keeping the % of clay rather high in the overall mix, then with proper compaction and moisture it can be bulletproof and much less likely to dramatically shrink and swell and fail. in affect like ewest illustrated, re-sorting your pond dirt so its poorly sorted and clay rich.

there are natural gravelly or sandy clay deposits out in our area that hold water really well (dug out by gravel companies) which is an extreme example of ewests pic on the right.

to further muddy the situation, there are lots of different types of clay (montmorillonite, kaolinite, bentonite....to name a couple) each having different properties, for example bentonite is a huge sweller which is why drillers and pond builders like it......kaonlinite is not. the word clay technically refers only to the grain size of the particles making up the soil, and there are many different types of clay sized particles.


GSF are people too!