Trying to problem solve the current situation with my above ground pool. It was professionally installed about 6 years ago. Land graded to level, patio blocks under each upright. It is about 3' from the property line with my neighbor, who has several ornamental type trees growing on the fenceline. One of the trees had a good size root cut when the yard was leveled for the pool and after the 1st summer the pool sank about 1" on that side and remained stable until this past summer. In 2011 we had a severe drought in Texas and the sewer main from the house snapped. The plumber dug out 6-8 feet of line and replaced it. The repaired part did not run under the pool but the rest of the line does. This is the same side as the fence. We have gumbo clay soil and that stuff can really shrink when it dries out. This year we had a lot of spring and early summer rain and now that whole side of the yard is noticeably lower. That side of the yard does not seem mushier than the rest of the yard, but the pool is now about 3" lower on that side. I don't see any buckling in the wall of the pool. I don't know if the soil shrank during the drought and compacted down after heavy rains and filled in voids left from rotting tree roots causing the pool to sink on that side or if something else is going on.
I know I am going to have to take down the pool and re-level the yard. The question is how do I find out what caused the ground to sink and how to prevent it from harming the pool in the future?