How can I look down there and see if the hole is the proper depth and width? an occasional building inspector will ask while trying to divine what is at the end of a 6'x 40' slurried shaft. Well, he can't. He can drop a weighted tape and check the depth. Sometimes he will be concerned about whether the hole's walls are larger than they should be at any location through slight caving. This partial underreaming actually provides a more structurally sound foundation when the concrete fills the voids.