Shortly after a 9:28 a.m. call the morning of Aug 17, 106 FDNY members arrived for the rescue, the Village Voice reported.
Robert Legall, a 56-year-old mechanic who was performing off-season maintenance work, suffered unthreatening neck and back injuries.
The vehicle is actually property of the Department of Corrections, and does work at Rikers Island prison.
Though there has been some suspicion of unsafe indoor speeding or a miscued gear shift into reverse, no clear determination for why Legall put the truck through a wall two stories high off the ground has been disclosed yet.
"The incident is still under investigation," DSNY spokesman Matthew Lipani said.