On Aug. 14, 1970, an underground river of coal began flowing 273 miles across the state of Arizona, and into a 1,500-Mw. power plant near Davis Dam in Nevada. Equivalent in capacity to two 160-car railroad trains per day, the unseen "river" is the 18-in.-dia. Black Mesa coal slurry pipeline, so far the largest and longest slurry pipeline in the world.
