When we were kids, we would visit my aunt and uncle in Queens NY in the summer on our way to my grandparents' bungalow on Long Island. They had a pool set up in their driveway in the backyard, under the concord grape vines. The bottom of the pool always felt soft, not at all like it was on concrete. My uncle said it was because they always put it on top of my aunt's old boyfriend, Pete Moss (peat moss) so maybe that would work.