has been building under it. >> reporter: well, you know, this is sort of the difference between the static kill and the top kill. during the top kill there wasn't the containment cap on top. they were able to keep pressures monitored by the engineers watching this. with the cap in place, they will be able to pump the mud and cement through the blownout preventer and down into the well during this procedure. and as the procedure is going on, those engineers are going to be taking pressure readings minute by minute throughout the course of the night, throughout the next 24 to 48 hours, and they are hopeful that as they do this they are not going to see any burps, any leaks of glass gas or oil out of this well, out of this containment cap. if all goes according to plans, and the pressure readings stay intact, they are reasonably confident this is going to work. >> jim, thank you for watching that for us and explains that to