Digging holes

We are digging holes were water has been sitting & that has damaged the turf, so we are digging through the clay layer & getting into free drain soil I'm hoping this will help dry up these areas but when water levels are high water won't drain away. we are digging down to a depth of about 6ft or more then we be filling them up with drainage material. We then turf them when done so have put a slab on top just for safety.