Hello all- Yes I am starting a project my wife says to finish(along with the others) Anyway, I have dug a 10 x 11 pond 24" deep. Backwalls are straight up and down, front of pond has some slant. Do I need to build a concrete wall along the inside to prevent it caving in? It's in pretty hard clay soil. I thought I'd frame up about a 2" wide wall and fill with quick-rite. Next...I am using a flexible liner. I also am building a waterfall. I was told to put the liner under the falls to prevent leaking. How do I do that- Thanks to all and great forum!