I'll tell you we had set our AG pool 'in-ground' below grade and after 10 years the side wall rusted thru. Now be aware we only put in mulch about 1' deep but after many years it turned to dirt. Even with the small amount of rain here in central tx. it was enough to corrode thru the wall from the outside-in. When we (IF) we replace the pool as it sits, I will ensure that no backfill touches the pool sides and keep the trench clean. That way even though water may temporarily fill up on heavy rains, it will drain and dry and no dirt or backfill will touch the pool wall to rust it again. Of course with the resin pool we're looking at it shouldn't take much if any maint. at all re:dirt or backfill agains the pool wall. Lesson learned.