Did you build the pool or inherit it by moving ? If you built it did they hit sand ? It would be pretty cheap to build a small berm or 1 block high retaining wall around the pool fence and sink a bunch of strategically placed 6 inch PVC pipes down to sand level. Fill them with gravel and some sort of grate and if the rain ever comes down that hard again it has somewhere to go.While I don't want to leave myself exposed I'm also not sure it's worth putting too much effort into safeguarding against the possibility we see something like that again. Famous last words, I know.
But. If your clay soil is 30 foot deep it becaomes less easy.