I have a pretty big slope in my backyard. Can someone advise me on the process of building up the front side of the waterfall. I have started digging, and in order to have a level surface area, I will need to build up about that much. The previous homeowner had a pallet of stones that were about the same amount, so I am looking for an idea where I can use the pallet of stones, without having to purchase thicker ones. Thank you.