instead of fluctuating with bursts of gas, bursts of oil that give them a hard time. if it really works they'll try to put some concrete down here and fill it up. it's important to remember, two pipes are here, big outside about like that and an inside one. if they do this, they'll fill the inside one, but the outside one will still be open. that's where we get to the next part of it, which is the relief well. the relief wells are coming in from the outside. they're getting much closer. if this works properly, what they will do is pump down into here after they cut in with the drill from the side and they'll pump concrete in, which would fill up that outside area and then they would follow it up by completing filling the inside area. all of that together would permanently seal this well off, randi. at least they hope. >> reporter: all right, tom. thanks very much for that. retired coast guard admiral thad allen, overseeing the federal response, said today the nearly constant flights that check for surface oil on the water from the air are barely detecting any oil beyond thin sheens.