Miners remove a 12-foot thick layer of rock some 150 feet underground, leaving a thick ceiling between the underground space and the outside world. A truck in part of Subtropolis. Costs for converting such spaces are low - the process mainly involves painting, pouring a concrete floor, wiring, and putting up a few walls. The relatively constant temperature, around 65 degrees, makes the old mines a useful place for long-term archival storage. Costs for insurance, taxes, heating and cooling, and security are also less underground.
Food companies use the space, saving on refrigeration costs.
The US Postal Service, the largest tenant of underground space in the area, uses mine space for fulfilling orders for stamps for collectors. A massive duty-free warehouse holds goods from around the world. Other uses for the space have included a college library, health center, and computer lab. An underground computer lab. On this hour of Science Friday, live from Kansas City, Missouri, we'll talk about the geology of the area, and the engineering considerations that go into constructing an underground city.