We put a good layer of sand down to level the area and then the blue tarp on top. walking around in the pool today brushing it...I felt a couple of dips when running the push broom along the bottom. Used my foot to feel and there are good sized cracks in the ground under the pool. Will this hurt the liner? I haven't filled the pool totally up yet..but really don't feel like draining it and taking the thing apart to fill the crack or move the pool. the cracks are about 3 inches wide and maybe about 8 inches long...give or take.