August 21, 2008

Water Tunnel Sees Daylight

By Andrew Edwards

SAN BERNARDINO - After close to five years of digging, the Metropolitan Water District's huge mechanized tunneler finished its journey underneath the San Bernardino Mountains on Wednesday.

Standing before an audience that gathered to see the Southern California water agency's $9million digging machine break through the surface at Devil Canyon, MWD board member Gene Koopman signaled a goateed worker named "Slim" to make the big phone call to miners in the mountain and let them know it was time to turn on the tunnel boring machine.

"Knock this sucker down," said Koopman, who is also an Inland Empire Utilities Agency board member.

The machine, of course, was still inside the mountain and out of sight. If not for the announcement that the mining crew had the green light to dig, it would have been impossible for anyone in the audience to know what was happening.

But minutes later, a faint sound came from inside the earth - something resembling the sound of marching, if heard from a great distance. Small pebbles shook loose from the gunite-stabilized rock face as the still-unseen boring machine pushed forward with tremendous, steady force.

Then finally, after a wait of mere minutes for the audience and years for the engineers and miners who worked on the digging, the rock at the end of the tunnel cracked.

The crack grew into a rupture, and shortly after 10:30 a.m. Wednesday, a chunk of material fell to the ground.

For the first time, sunlight entered what engineers call the Devil Canyon portal, and the audience could see the spinning face of the boring machine as it grounded away at the remaining rock.

The audience cheered. Richard Strauss' "Thus Spoke Zarathustra" - best known as the theme music to "2001: A Space Odyssey" - played from speakers and joined the surprisingly soft noises of crumbling rock.

The business end of the boring machine is equipped with 39 steel discs that are designed to press against rocks as the mechanical behemoth inches forward along its underground path. The machine face rotates counter-clockwise as it grinds rock into dirt.

But with the new portal about halfway dug, the machine stopped. An MWD engineering manager explained that the mechanism can only move five feet at a time, since the mining crew working behind the machine must install concrete barriers to prevent groundwater from seeping into the freshly cut tunnel.

So it was time to wait a few more minutes before the digging could resume again for the final stage of the dig.

For the MWD, the work's not over. The new 3.8-mile tunnel linking the Devil Canyon and Waterman Canyon areas is part of a 44-mile system called the Inland Feeder Project designed to carry State Water Project supplies to the Diamond Valley Lake reservoir near San Jacinto.

"The project is about being able to get water when it's available," MWD general manager Jeff Kightlinger said.

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