...over here in construction we use "backfill" rather than "fill that hole you just dug back up". I don't mind it in that context at all.
My dad had a summer job 'backfilling' motorway bridges - filling in by hand (well shovel) the gap left Inbetween the road and the new bridge. So I assumed in meant filling in a gap left by a bigger piece of work.
Yeah, that sounds about right: Dig a big hole, build a bridge abutment in the middle and 'backfill' around it. I think I would say 'fill' for building up a new area of ground, like a motorway embankment or something.
Never heard it in the context of filling vacancies though!
My dad had a summer job 'backfilling' motorway bridges - filling in by hand (well shovel) the gap left Inbetween the road and the new bridge. So I assumed in meant filling in a gap left by a bigger piece of work.