nice job! I wouldn't completely write off concrete. One could always sandwich concrete with liner. That's what I've done and a tree root lifted up the concrete and cracked it but it still works.
While if the liner somehow breaks inside the concrete (unlikely), I've experimented with the sandwich technique regarding a tear where two pieces of pvc were glued together and came apart. The solution was to throw fine clay in the water, it self seals the area inside the crack where a liner is torn.
I'm totally sold on sandwich technique as our hounds enjoy splashing around on the concrete with no worries. As far as I know, I'm the only person in the U.S. to use this technique. I learned it from someone in the U.K.
