There's a scene in a Stephen Crane story in which a bunch of poor men are crowding around the door of a charity house in the snow waiting for it to open, and stepping on each other to get closer to the door; in it one curses at another and says

"Git off me feet, yeh clumsy tarrier!"

"Say, don't stand on me feet! Walk on th' ground!"

Combined with the definition as an augur or boring instrument and the fact that they did work near blasting (based on the premature blast verse in the song) I suspect I was right -- they drilled the long narrow holes that got filled with dynamite to blast away rock from the face of a tunnel.

And they were clearly not highly thought of, from the context of Crane's usage.

A