excavation and backfill definition
The definition of backfill is material used to refill a hole, usually what was previously dug out of the hole. Dirt and gravel are examples of backfill. Backfill is defined as to return soil and other materials to a hole after it was dug.
OSHA defines an excavation as any man-made cut, cavity, trench, or depression in the earth's surface formed by earth removal. This can include excavations for anything from cellars to highways. A trench is defined as a narrow underground excavation that is deeper than it is wide, and no wider than 15 feet (4.5 meters).