I am going to be leveling and doing a lawn renovation over a 2 year old septic field. The homeowner has been running a drag across it for 2 years trying to level it.?? I am going to be adding good topsoil to level. Is there anything I need to know about this besides not to run too much weight on it? He has never gotten seed to grow on it. Oh, and it is part shade, part filtered sun.