"Deep shaft rescue" is an informal term used to describe confined-space rescue situations involving victims trapped in pipes, wells, and other vertical shafts--in essence, vertical, belowgrade confined spaces. The Occupational Safety and Health Administration (OSHA) defines a shaft as "any excavation more than 20 feet in depth whose depth to width ratio is 5 to 1 or greater." Deep shaft includes all vertical mines; ventilation holes for subway systems; bore holes for deep pilings at construction