Howdy, all. Perry - from New Zealand - checking in.
After poring over more than few threads, I have the sinking feeling that my aspirations border on lunacy. My proposed pond area is modest, by USA standards. It'd be measured in square yards, rather than acres. My guess is about 40 x 20 yards, in an ovoid shape. Probably not going to be much more than 2 feet deep.
The water supply will be replenished constantly from the output of a biocycle aerobic/anaerobic waste-water treatment system. Essentially the supernatant from black and grey water from five households on the place.
However, the system does not work as it should, with more suspended solids in the supernatant than there should be. The good part about that is those fine, sus- pended solids do seem to act as a sealer, of sorts. There is no serious or nasty septic tank-like odour.
So, if I am lucky enough to get the project close to reality, the inflow will tend to facilitate sealing. The seems a fair presumption, based on leaving the output hose on the shingle, and watching the water spread further, over the months. Besides . . .
I plan to have a flowform on the island, to achieve aeration /good water quality. What's a flowform, did you say?
The real obstacle here is the 'soil' strata. Stony gravel with some silt overlay is how it's described. And I've dug enough post holes to be sure of that. As I see it, bringing in a high clay content soil and hand-plastering it is among my few (natural) options.
I also suspect that the bentonite clay in New Zealand is not of the same quality or make-up of what you folks have access to. Not even sure if New Zealand-purchased kitty litter would be better!
Among the DIY crowd, has anyone tried - say - mushing soaked old newspapers pulped together with bentonite? (A variation on the gley option?) Other variants? Yes, I did read of the alfalfa experiment!
