One of the History Channel's documentaries on the carving has a snippet of the last guy on the mountain finishing up work for the day, hanging down the side in a bosun's chair.
The dynamite had been placed, ready to be set off at the end of the work day (to allow the dust and debris to settle over night), however, a storm moved in and lightning set the blast off.
The guy had his boots blown off, but was back at work the next day.
The dynamite guys would get headaches from touching the nitroglycerin when cutting the sticks down to the needed charge size.
:’) I wonder if he worked barefoot?