Drilling the holes for concrete removal

See how high up on the building he is standing? Normally the footer is several feet down in the ground. There is a 3 foot high crawlspace under this church, so he should be standing up to his waist. That gives you an idea of how much extra concrete has to be removed. The reason for drilling holes is to have nice clean breaks when using a jackhammer. This makes less chance of harming the building itself.