So I've decided to use Western Liner to provide a 40mil RPE liner. I just don't want to worry about leaks so that is the direction I've gone.

That said, I'd like to create the best fish habitat I can so should I line the bottom with soil and work from there. In a previous thread I've asked if anyone has had success retaining soil on the 3:1 slope on the sides of the lake/pond. Whether or not that is possible, I certainly can line the flat bottom with soil to promote habitat but I'm a noice and need advise.