[Dale Wiley]

This is what is so great here.... what a trove of information.

20 mil is less than 1/2 the thickness. I would be very hesitant to use a 20 mil liner. The 3400# thing is cool, but 20 mil is just to thin in my humble worthless opinion.

I have done several of these, and we always did them in summer, and rolled them out in the excavated area, and seamed them together right in the pond, (no water). We used a glue process on one, and the other I subed out to a dirt company that has some kind of heat glue gun from Martha Stewart or something.

That one was put in in Las Vegas area, in calichie soils, crumbly but fairly smooth after you took an excavator to the walls and bottom.

You only want to roll that bad boy out once and once only.

I would almost think about getting a soil engineer involved here and have some specs developed that you can install to. CYA.