Best thing is to take it home and fill it with a hose a couple of inches.Make sure it is flat and wait a while.You'll see it dripping.You can hammer them rivets from the outside with a person holding a metal dolly or hammer on the same rivet from the inside while you hit it from the outside.It's worth a try,just might do it.If not you could silicone the rivet both sides with a little brush.