SNWA tunnel boring machine

The scale of the “third straw” Las Vegas is poking into Lake Mead is one of those made-for-journalism anecdotes that tells the story of a great western city’s thirst.

The new intake is insurance that Vegas can still get water from Mead if lake levels drop below intakes one and two, a tacit admission of the realities of the supply demand mismatch on the Colorado. Like I said, an anecdote made in journalist heaven, a big problem reified by massive engineering and fancy gizmos. What does Las Vegas think of its its down side risk? Enough that it is willing to do this:

Southern Nevada’s newest piece of mega-hardware—a custom, $25-million Herrenknecht tunneling boring machine—makes its long-awaited underground debut later this year.

The machine works like a giant mechanical earthworm, gnawing through dirt, rock and muck, forming a protective tunnel that will eventually channel raw Colorado River water onto nearby treatment plants before being pumped to homes and businesses throughout the Las Vegas valley.

The 1,800-ton, 600-ft-long TBM is the workhorse of a $526.6-million third raw-water intake tunnel project at Lake Mead, 30 miles southeast of Las Vegas. A joint venture of S.A. Healy Co., Lombard, Ill., and Impreglio S.p.A., Sesto San Giovanni, Italy, known as Vegas Tunnel Constructors LLC, is the design-build contractor.