With a loud roar and a cascade of dirt, a 250-ton mechanical mole punched through the earth's surface recently, leaving in its wake a large-diameter tunnel, 8 miles long, to serve as a critical water line for Southern California.
The breakthrough completes the 220-foot-long tunnel boring machine's year-and-a-half journey through the rocks and dirt up to 800 feet beneath the Badlands mountain range in Riverside and San Bernardino Counties, as part of Metropolitan Water District's Inland Feeder project.