I am trying to put up my first pool, and starting small so I purchased a intex 15X4 pool with metal poles. The problem is my ground is slightly on a hill and is very rocky (bluff). I understand I have to dig out the high side and level from there. The question is will sand packed down be enough to protect the pool from the rocks or should I use a foam padding also. If so in what order should I lay the foundation? I would appreciate any advise.