kengr

BSCE writing, here. However, I have very little actual experience with heavy construction.

I'm reminded of the reaction of the foreman of the concrete pouring for the Hoover Dam to rumors about workers being drowned and buried in the concrete and the bodies just left: "That would weaken the concrete!"

Anway, there is so much work done with modern concrete (for example, most foundations for large buildings have reinforcing steel put in place before the pour, then the concrete is tamped or vibrated to ensure there are no voids) that having a body go unnoticed is unlikely. OTOH, for an older building, or a large, modern home (especially one with unusual specifications by the architect or contractor) which has massive, non-reinforced concrete foundations such a disposal might be feasible. There is a black comedy movie (I want to say _The Gazebo_ with Jack Lemmon in the Sixties, but am far from sure) about a guy who buries a body in the poured concrete foundation of a new gazebo on his property. This backfires when the foundation literally falls apart during a heavy rain, probably because of the body. ("The savage gazebo attacks!")

More feasible is finding a body (probably just bones and teeth even after only a few years, unless the soil blocks decay) which is uncovered by modern excavation. I read about that happening pretty frequently. It's usually prehistoric, early historic or medieval, but sometimes later. Rarely, much later.

I believe the method of starting a pile varies with the constructor. Some may have a reusable guide to start flush with the ground for each piling.