Interesting place, but I'm thinking it was kind of a short lived boot strap operation, maybe active as late as the 1950s. In the mine at worked at in the 70s and early 80s many of the senior miner's, with already as much as 30 plus years by the time I got there, had before served in Korea, Vietnam and one old fella even finished his time in Europe as a German pow after his B17 was brought down. The term, Just, jerry-rigg the sob, was often used back then and you knew what it meant. Now days it describes something you should not have done as an improper fix to a situation. Heck you might even be subject to corrective action if you used the practice of jerry rigging. I think today it describes it was something that slipped through the approval of the engineering department.