In an area with a high ground water base and a mixture of clay in the soil, fiberglass pools, without a cantilevered concrete surrounding deck, can pop up out of the ground and float in the surrounding water and mud.
FYI: Don't store batteries on concrete floors, best to keep them at least a inch off the floor or on a shelf. I can change two 28 volt batteries in a 757-200 quicker than it would take in my car... Open access hatch, disconnect temp sensor cannon plugs (one each battery) cut co...