I'll second this. And a 12" tall concrete platform will also make it easier to get in and out of the safe. And something you can bolt it down to. Amd if you get a little flooding, your stuff will be good.May want to consider building up a 3-6" or so layer of concrete under the safe to hopefully prevent water getting in the safe in case of a minor flood like a water line break or sump pump failure. Major flooding not much you can do if you aren't home when it happens.