After leveling the ground, is it common to add something around the perimeter to keep the sand in such as the plastic landscaping edging or landscaping bricks, or does the sand just get spread across the site evenly and level and it stays in place good after compacting manually and with the pressure of the pool’s weight? Also, if there is about a 4” drop on one side of the site, does this ever cause any problems in the future or is there something to do for that as well?This is my first pool so I’m trying to get everything right. Thanks!