I have built many waterfalls for ponds but not for pools. We are being asked to demo existing waterfall which looks like a pile of rocks and build a new one with a smoother fall. This will be easy as I know what type of rock to use and how to construct it. I guess where I am having the problem is how do I build up the overall stream and waterfall? Do I use the stone to build retaining walls then backfill with soil and tamp until I get the height I want then set the liner in? do I use concrete block underneath to stabilize? Essentially I am afraid of the stream settling out. How would you guys prep the area to build a fall that starts out at 3' high, approximately 8' behind the pool. They really want the stream/fall area naturalized with plantings but,I also don't want this thing to put debris into the pool. Help!!!!!!!!